bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear strength parameters of peat soil of district of Asahan by direct shear test
Authors: Roesyanto  , Ritonga A. S.
Published: June 2020

Peat is a wetland ecosystem characterized by the accumulation of organic matter happens for a long time. This accumulation occurs because of the slow decomposition rate compared to the rate of accumulation of organic found in the wetland forest. The purposes of this study were to determine the index properties, to classify the peat soil classification, to obtain the optimum water content and maximum dry unit weight, γd by Standard Proctor test, and to examine the shear strength of peat soil by direct shear test. The peat soil had water content, w of 726.34 % and a specific gravity, Gs
of 1.302. Based on ASTM D4427-92, the classification of peat soil was high ash peat and highly acidic. Based on the Standard Proctor test, the optimum water content obtained was 34% and the maximum dry unit weight was 0.518 gr/cm3. The Standard Proctor test increased the value of the dry unit weight of the undisturbed soil samples from 0.154 gr/cm3 to 0.556 gr/cm3. The original internal friction angle, ϕ and cohesion, c were 0.595º and 0.019 MPa while the Standard Proctor test resulted in 3.539º of internal friction angle, ϕ and 0.020 MPa of cohesion, c.
The ambiguous identity of Lumban Bulbul
Authors: Siagian Morida , Sitorus Rudolf
Published: June 2020

Lumban Bulbul Beach, located on the bank of Lake Toba, the North part of Balige City has transformed rapidly in the last 5 years from qualitative to quantitative values. The space of village for daily life with the use-value of living focused on family and agriculture and livestock, today has become commercial activities space with exchanged value. The government of Toba Samosir District intervenes the beach construction to show the progress of development. For decades, community planted bamboo along the beach as wind defenses and maintains fish life and farming, but today transformed into the recreational beach with food and beverages stalls of the community. The local wisdom is ignored and exploited for commercial purposes. The orientations of the houses gradually turn towards the beach for serving modern recreational life. The dualism of life occurs in the area is creating ambiguity, one side as the local community’s daily life, and the other side to gain profit. The research conducted by quantitative method with the observation of space, activity, users, find the ambiguity of the house along the beach, between daily life space with use-value of the community for several generations, and modern commercial space along the beach with exchange-value.
Production of biodiesel from used cooking oil using blood cockle shell (Anadara Granosa) ash as catalyst
Authors: Sinaga M S , Petrus Bernandus , Sitompul W G T
Published: June 2020

Biodiesel is renewable energy that can be renewed, biodegradable and enviromentally friendly. Transesterification is a reaction which is used to produce biodiesel where this reaction uses catalyst which was made from blood cockle shell ash which has been combusted at the temperature of 850°C for 3 hours and the amount of the ash being used was 8%, 10% and 12% (m/m). The ash used was dissolved into methanol with the mole ratio of methanol to oil of 9:1, 12:1 (n/n) to obtain calcium methoxide. Used oil was filtered then esterificated by 3% of catalyst (m/m), H2SO4 98% and methanol:oil TG (6:1) to reduce the FFA until it is less than 1%. Transesterification was done at the reaction temperature of 65°C for 3 hours and constantly stirred at the speed of 700 rpm. Quantitatively, optimum biodiesel yield obtained was 56.51% at the condition of 12% (m/m) of blood cockle ash, 12:1 mole ratio of methanol to used oil. The specification of the biodiesel such as density, kinematic viscosity and flash point at this condition matched the standard of biodiesel SNI 04-7182-2006 and according to gas chromatography analysis, the purity of the biodiesel produced is 98.79%.
Biogas production from tofu wastewater substrate using HUASB reactors with addition of trace metal
Authors: Afrizal Azis , Yandari Fitri , Kurniawan Sandi , NyimasYanqoritha  , Razi Fachrur , Munajat
Published: June 2020

Tofu liquid waste contains a high organic load so that the processing system is needed to reduce the pollutant parameters in the wastewater to fulfill the quality standards. The most suitable treatment for organic loads is anaerobic processing. One anaerobic processing system uses the Hybrid Upflow Anaerob Sludge Blanket (HUASB) reactor with the consideration that this reactor has the advantage of maintaining high amounts of biomass concentrations, high load rates for operation, good deposition capability, and good solid-liquid separation due to appropriate granulation. The purpose of this study was to determine the effect of adding trace metal FeCl3 to the removal of COD, TSS and biogas production on tofu wastewater treatment at the HUASB reactor. The process of tofu wastewater treatment with the addition of trace metal in the HUASB reactor using a batch circulation system with a reactor volume of 9 liters. The reactor is operated by variations in the concentration of tofu wastewater (75 and 100%) and trace metal concentrations (0.3-0.6 mg / L). The parameters observed in this study were pH, COD, TSS, and biogas produced. The results showed that the optimum biogas production of 8.190 mL at the concentration of tofu wastewater was 75% with the concentration of trace metal 0.6 mg/L and allowance for COD and TSS of 94.09% and 94.02%.
The accident risk of motorcyclist perception and driving behaviour: a case study
Authors: Nurul Huda Listiani , Puspa Sari Lubis Indah
Published: June 2020

A traffic accident is an incident that is unexpected and involves a vehicle with or other road users resulting in human casualties or property losses. Accidents are caused by several factors including environmental factors, vehicle factors, and driver factors. Traffic police noted that in 2017 there were 91,371 traffic accidents caused by driver factors. Bad driving behaviour causes driving distraction which is an important risk factor in traffic accidents. This happens because the driver perceives a risk that is smaller than the actual risk. The purpose of this study was to see the existence of a significant relationship between risk perception and driving behaviour towards the risk of motorcycle accidents(H0). Case study took place in Industrial Engineering Department, Faculty of Engineering, University of Sumatera Utara. Data were collected using research instruments in the form of driving behaviour questionnaires which consists of two indicators namely obedience and pride, risk perception questionnaires which consists of two indicators namely worry and social pressure, and traffic accident risk questionnaires which consists of three indicators namely declaration rate, respond to accident, and braking distance. Then a Structural Equation Model (SEM) was made. The results of the Structural Equation Model (SEM) show a significant relationship between risk perception and driving behaviour with a t-value of 1.98. This indicates that worry and social pressures have a significant direct effect on drivers’ behaviour.
Extraction of sambung nyawa leaves (Gynura Procumbens [Lour]. Merr) using methanol as solvent
Authors: Suriani Sinaga Mersi , Defriska Siagian Putri , Meidinah Shintia
Published: June 2020

Sambung nyawa leaves (Gynura Procumbens [Lour]. Merr) is used as traditional medicine. Sambung nyawa leaves contain flavonnoid compound which can be used as natural antioxidant. This research was done to analyze the effect of the additon of Sambung Nyawa leaves extract as antioxidant and its ability to keep the quaity of coconut oil. The variables used in this research were the ratio of raw material to solvent (m/v) and extraction temperature. First, extraction was done to extract flavonoid compound from Sambung Nyawa leaves. The extract of Sambung Nyawa leaves with the highest flavonoid compound was mixed with coconut oil for 3 days, 6 days, 9 days, 12 days and 15 days. Total flavonoid level from Sambung Nyawa leaves was analyzed by UV-Vis Spectrophotometry. Acid number, iodine number and peroxide number of the coconut oil were also analyzed in this research. The highest total flavonoid level obtained was 1.32% at 55°C by using 1:10 (m/v) of raw material to solvent ratio. The lowest acid number, the highest iodine number and the lowest peroxide number in coconut oil with Sambung Nyawa leaves extract after it was kept for 3 days were 0.45%, 7.90g I2/100g and 4.40 mg O2/100g respectively.
Application of ranked positional weights method in springbed production line balancing
Authors: Siregar Ikhsan
Published: June 2020

In the current era of globalization, business competition demands industries in manufacturing to improve their business strategies are increasingly. The company that produces spring beds of various sizes has experienced rapid development. Spring bed 180 cm x 200 cm size has the longest process and research on the springbed production line is 180 cm x 200 cm. The company has 9 work stations with 19 work elements with time variation of work elements which are 50 seconds to 2737 seconds. The problem experienced by the company is the bottleneck at the assembly station because it has the longest cycle time of 2737 seconds. One method used in assembly line balancing is the RPW method (Ranked Positional Weights). The RPW method is an approach to solving problems in line balance and finding solutions quickly by the number of workstations determination at a minimum by giving weight to each work elements that has been placed on all work elements. Using the RPW method, obtained line efficiency, balance delay and smoothing index were 86.09%, 13.91% and 1418.45 with the number of work stations is 8.
Design of work facilities using quality function deployment (QFD) and macro ergonomic analysis design (MEAD)
Authors: Tambunan M M , Napitupulu H L , Rizkya I , Syahputri K
Published: June 2020

XYZ is a company engaged in the manufacturing of doors. XYZ process consists of 7 work stations, such as sorting of raw material, the unification of the core material, reaping, laminating, manufacture of components, finishing, and packing. Among 7 work stations, only 1 work station to work while standing still during work (8 hours) and do not have other work that supports the position that the work station finishing work. The purpose of this study is to make improvements to the facilities at the finishing work desk. Facility design work is done by using quality methods to obtain technical characteristics in accordance with the desire of works. Furthermore, the results of the design tool socialized to all component companies use macro ergonomic analysis and design (MEAD). From the result of the design was found that the workbench is design to have the specification table legs fixed, material frame of iron, base material of foam, base material of leather, color frame brown, place mats of blue, the durability of the table at least 3 years, and additional function where the laying equipment. Result are discussed with the company designing and disseminated to the component companies
Simulation process unit bleaching in cooking oil plant using super pro designer version 10.0
Authors: Irvan  , Suharmanto A , Sidabutar R , Ashari M
Published: June 2020

The bleaching process is one of the processes in the manufacture of cooking oil that serves to absorb the gum, moisture content and color in crude palm oil. Role of color in the marketing of cooking oil is very important, because, in general consumers tend to use the color parameters as the quality of cooking oil. The use of programs to facilitate the design of a process such as Super Pro Designer, Aspen, and Hysys is a way to increase the profitability of an industry. This study aims to provide information that Super Pro Designer applications can simulate the bleaching process contained in the cooking oil plant. Method used was simulated data obtained from the plant using Super Pro Designer Version 10.0. The result showed that at feed flow rate of 86,000 kg/hour the temperature of 100 °C was obtained as output of plate heat exchanger.
Computer simulation of horse shoes made of polymeric composite subjected to external loading
Authors: Syam Bustami , Muttaqin Maraghi , Siregar REK , Rozy Fakhrur
Published: June 2020

A horse shoe is designed to protect a horse’s hoof from wear. Like the human shoes, the horse shoes should also meet the ergonomic design, i.e. strong enough to withstand external loadings, comfort, and safe. Conventional horseshoes made of iron, for example, have good mechanical properties, but they are not comfort enough for horses due to its higher weight to size ratio. The internal stresses due to the external loading of the shoes to the soil surface, rocks, asphalt or hard surface will transfer the force of the horse’s foot pounding against the horse’s foot, so that it can hurt the horse’s foot if used for a long time. Therefore, a new research on polymeric foam alternative materials is the main concern to reduce existing problems. The purpose of this study was to conduct a static loading simulation of horse shoes made of polymeric foam reinforced with glass fiber using ANSYS software. In the simulation specimens are modelled with SolidWork. The aims are to determine the stress distribution of to two horse shoes models. It was found that the stresses on z-direction for both commercial and polymeric composite horse shoes material were not significantly difference in values. Stress in z-direction constitutes the bending stresses due to external loadings. The stress contours on both modes are also similar. The stress concentration occurs around the vicinity of the shoe connectors. The maximum normal stresses in z-direction at those locations for steel and polymeric composite are 7.819 MPa and 7.850 MPa, respectively. Comparing those stresses with the static tensile strength of both materials we may conclude that both horseshoe structures are acceptable to be used. However, in terms of the applicability the one made of polymeric composite are more easily to be used.
Discrete system simulation application on determining the optimal amount of weekly production
Authors: Napitupulu Humala L
Published: June 2020

PT. MNO produces egg trays to serve requests from 4 Distribution Centers (DC) in 4 regions, namely DC1, DC2, DC3, and DC4. Delivery of products to meet all DC requests is done once a week. Sometimes, supply shortages occur when the total weekly production and initial stock is lower than the total demand. This shortage of supply results in loss of opportunity. While in other weeks there is excess inventory which causes storage costs. Shortage or excess stock is related to the absence of production planning and determination of weekly production plans. Therefore, the optimal amount of weekly production needs to be determined using a system simulation. Simulation models are designed and translated into formulas in Microsoft Excel worksheets. While data on the number of requests is generated by using the weekly demand distribution pattern as a reference. Discrete system simulations are run by experimenting on nine levels of total weekly production. The output obtained includes the number of requests that can be fulfilled, the weekly ending stock, the number of shortage, the amount of excess stock, and the total profit. Simulation results obtained can indicate the optimal level of production.
Performance improvement strategies to increase call center service level: a literature review
Authors: Sihol Marito Purba Johana , Hidayati Juliza
Published: June 2020

Call centers are an increasingly important part of today’s business world, employing millions of agents across the globe and serving as a primary customer-facing channel for firms in many different industries. Call centers have been a fertile area for operations management researchers in several domains, including forecasting, capacity planning, queueing, and personnel scheduling. Also, as telecommunications and information technology have advanced over the past several years, the operational challenges faced by call center managers have become more complicated. Issues associated with human resources management, sales, and marketing have also become increasingly relevant to call center operations and associated academic research. In this paper, we provide a survey of the recent literature on call center operations management. Along with traditional research areas, we pay special attention to new management challenges that have been caused by emerging technologies, to behavioral issues associated with both call center agents and customers, and to the interface between call center operations and sales and marketing. We identify a handful of broad themes for future investigation while also pointing out several very specific research opportunities.
Effect of surface treatment on tribological characteristic of ferrite nanoparticles epoxy composites
Authors: Singh Ashtosh Kumar , Zaidi M. G. H. , Saxena Rakesh , Suman Rajeev , Maheshwari Peeyush , Gangwar H. P , Rawat K. S. , Verma A.
Published: June 2020

In this investigation, surface treatment of ferrite nanoparticles were efficiently prepared by using amino propyl silane (APS). XRD which is a spectral analysis technique used for investigate the morphology and chemical structure of treated and normal ferrite nanoparticles. Ferrite nanoparticles epoxy composites were prepared by Modified ferrite nanoparticles (MFNs) with varying weight percentage and ferrite nanoparticles (FNs). XRD shown that MFNs was effectively modified with highly crystalline structure and silane surface treatment decreased the average particle size of FNs to ∼ 16.48 nm. Surface treatment of FNs enhanced the homogeneous dispersion of ferrite in epoxy resin and improved interfacial adhesiveness between MFNs and epoxy. Tribological property of Modified ferrite nanoparticles epoxy composite (MFNEs) compare to cured epoxy and normal ferrite nanoparticles epoxy composites (FNEs) has been enhanced due to surface treatment.
Evaluation of impact and hardness properties of Al 6063-AgNPs composites produced by stir cast technique
Authors: Mudashiru L , Adeodu A , Awodoyin A , Bello A , Oloyede O , Aiyedun P
Published: June 2020

The effect of silver nanoparticles (AgNPs) on the mechanical and microstructural properties of aluminium 6063 alloy was investigated. Aluminium 6063 matrix was homogenously mixed with AgNPs impregnated with calcium carbonate at 2, 4 and 6% weight fractions. The mixture was used to produce refined samples through stir casting method. Measurement of impact strength and hardness property of the produced samples at ambient temperature was done by using Charpy impact and Brinell hardness testing machine in accordance with ASTM E23 and ASTM E384 respectively. The impact energy values (234-247 J) of all the samples with AgNPs/CaCO3 reinforcements were higher than the as-cast Al alloy (228 J) while the sample with 6% AgNp has the highest energy impact (247 J). Similarly, the hardness values (56.49-183.70 BHN) of all the samples with AgNPs/CaCO3 reinforcements were higher than the as-cast Al alloy (38.05 BHN) while the sample with 6% AgNPs has the highest (183.70 BHN). The magnitude of impact and hardness increased evidently with increase in percentage weight fraction of the AgNPs. The fracture images of the impact test samples revealed that the surface of AgNPs (CaCO3)-Al6063 composites were with dimples and there was a micro-void formation in CaCO3-Al6063 composite. The use of stir-casting technique influenced the homogeneity and microstructure of the AgNPs composites positively. The Al 6063-Ag nanocomposites possess better qualities in terms of impact energy and hardness, likewise can replace conventional aluminium alloy based on its performance.
Spectroscopic, microscopic and electrical characterization of nanoscopic polyindole DNA-templated nanomaterials
Authors: Yahaya MI
Published: June 2020

There has been an increasing demand for in expensive, accurate, movable and reliable nanomaterials for nanoelectronics devices and other applications. Deoxyribonucleic acid has robust nature, therefore it self-fabrication with indole can produce highly organised functional nanostructures that are of great interest for chemical industry applications. This research work is concerned with the synthesis, spectroscopic, microscopic and electrical characterisation of hybrid polyindole (Pln) DNA templated nanowires. Polyindole (PIn) has been templated on λ-DNA via oxidative polymerisation of indole using FeCl3to produce conductive PIn/DNA nanowires. The formation of PIn/DNA nanowires were verified by FTIR, UV-vis and XPS spectroscopy techniques. AFM, SEM and TEM techniques were used to characterise the nanowires dimensions. AFM studies revealed an average height of 1.60 nm for free DNA and the Pln/DNA nanowires have diameters in the range 2−15 nm with the dominance of 3-4 nm mean diameter range. The electrical properties of Pln/DNA nanowires as drop-cast films were investigated by two-terminal current voltage (I-V) measurements on a probe station. The nanowires were drop-cast (5 μL of as-prepared dispersion) onto platinum microband electrodes. The conductance of these films at 20 °C was of the order of 10-100 μS. In addition, the conductance of PIn/DNA nanowires exhibits Arrhenius behaviour (Ea = 0.80 + 0.06 eV) as a function of temperature. The above results have revealed the potentials of the Pln/DNA nanowire in nanoelectronics applications.
Optical studies of titanium dioxide/silver/gold (TiO2/Ag/Au) nanocomposites as photo anode in dye sensitized solar cells
Authors: Ogundeji ST , Awodele MK , Oyeshola HO , Adedokun O
Published: June 2020

In dye-sensitized solar cells (DSSCs), the performances of the photo anodes depend on the bandgap of semiconducting nanomaterials. Titanium dioxide (TiO2) is usually used in preparation of photo anode but it absorbs only the ultraviolet light, owing to its large bandgap of about 3.2 eV, and another drawback is that TiO2 has low electron mobility. In this study, optical studies of (TiO2/Ag/Au) nanocomposites as photo anode were carried out in order to test the possibility of improving the efficiency of the DSSCs. Dye molecule was extracted from the leave of sensitive plant (Mimosa pudica) using ethanol as solvent. TiO2/Ag/Au were deposited on a glass substrate using doctor blade method; the deposited thin films were annealed in a furnace at 450 °C for 1 h after which the annealed thin films were dye loaded for 12 h with Mimosa pudica extract. The dye loaded thin films of TiO2/Ag/Au were then characterized with a UV-vis spectroscopy to get the transmittance. The absorbance and the optical band gap were calculated. The optical absorption spectra and optical bandgap spectra of TiO2/Ag/Au thin films were examined. The maximum absorption was observed within the range of the visible region when the position of TiO2/Ag/Au is of volume ratio 1:1:0.8 and optical bandgap of 3.75eV. Anticipatedly, the performance characterization with further review on TiO2 with Ag/Au nanocomposites using M. pudica extract, as a sensitizer will enhance the development of an authentic and competitive dye sensitized solar cell.
Evaluation of microalgal-based nanoparticles in the adsorption of heavy metals from wastewater
Authors: Adenigba VO , Omomowo IO , Oloke JK , Fatukasi BA , Odeniyi MA , Adedayo AA
Published: June 2020

Bioremediation remains an eco-friendly and inexpensive method employed in getting rid of the toxic compounds like heavy metals present in wastewater. Different microorganisms are being used in either removing or reducing the concentration of heavy metals in wastewater but microalgae have a high affinity for heavy metals. In this study, nanoparticles from microalgae were evaluated for the potential to absorb lead and zinc from pharmaceutical effluent. Silver (AgNPs) and gold nanoparticles (AgNPs) were synthesized from both Nannochloropsis sp (NN) and Chlorella vulgaris (CV). The nanoparticles were introduced into a pharmaceutical effluent and the mixture was allowed to interact for 48 h after which the concentration of zinc and lead was determined using atomic absorption spectrophotometer. The AgNPs of Nannochloropsis sp (NN-AgNPs) and C. vulgaris (CV-AgNPs) had percentage reduction of 70.35 % and 74.62% respectively for zinc. Also gold nanoparticles of Nannochloropsis sp (NN-AuNPs) and C. vulgaris (CV-AuNPs) had percentage reduction of 60.32% and 66.83% respectively for zinc. The concentration of lead was reduced by CV-AgNPs (66.10 %), NN-AgNPs (68.86%), CV-AuNPs (57.41%), and NN-AuNPs (66.53 %). This study has established algal based nanoparticles as adsorbent with affinity for heavy metals and can be adopted for bioremediation of wastewater.
Ecofriendly production of silver nanoparticles from the seeds of Carica papaya and its larvicidal and antibacterial efficacy against some selected bacterial pathogens
Authors: Aina AD , Owolo O , Adeoye-Isijola M , Olukanni O D , Lateef A , Egbe T , Aina FO , Asafa TB , Abbas SH
Published: June 2020

Carica papaya seed extract (CPE) was used in the synthesis of silver nanoparticles (AgNPs) in this study. For the characterization of biosynthesized particles, UV-vis spectroscopy, FTIR, FESEM and EDX were used. Antimicrobial and larvicidal efficacies of the synthesized AgNPs were assessed in the fight against certain pathogens and the Aedes aegypti 4th instar larvae. The absorption spectrum of AgNPs peaked at 433 nm with a broad peak of 3000 to 3800 cm−1 for different functional groups as presented in the FTIR analysis. A FESEM evaluation revealed a number of spherical particle structures with an average of 20-69 nm. With zones of inhibition between 10-24 mm, the AgNPs synthesized inhibited selected microorganisms. After 12 h of exposure, the nanoparticles had LC50 and LC90 lethal concentration on the Aedes aegypti larva at 14.56 and 33.89 μg/ml respectively. This study demonstrates possibility of using Carica papaya seeds in AgNPs synthesis.
Green synthesized novel silver nanoparticles and their application as anticoagulant and thrombolytic agents: A perspective
Authors: Azeez M A , Durodola F A , Lateef A , Yekeen T A , Adubi A O , Oladipo I C. , Adebayo E A , Badmus J A , Abawulem A O
Published: June 2020

Effective management of haemostatic disorders in patients is pertinent in order to prevent complications attributable to incidences of thrombosis in atherosclerotic arteries to the heart, brain, limbs, stagnant blood in veins and heart chambers. The use of existing chemical agents are not without a number of challenges, varying from potential for unknown long-term adverse effect through lack of antidote for most agents, balance between cost and efficacy among others. However, advent of biogenic silver nanoparticles with anticoagulant and thrombolytic potentials has opened up a window of opportunity to address most of the shortcomings of the chemical synthesized anticoagulants. This review examined green synthesized novel silver nanoparticles, their characterization and possible application as anticoagulant and thrombolytic agents in the evolving area of nanomedicine.
Based on Bionic Optimization Design and Strength Analysis of The Tie Rod of Aircraft Landing Gear
Authors: Tang M T , Wang Q , He G Y , Liu R P
Published: June 2020

Based on the three-dimensional model of the cross-type tie rod in the landing gear of an aircraft, the mechanical analysis and solution are carried out, and the stress nephogram as well as the maximum position are obtained. Based on the analysis of bamboo microstructure, two kinds of imitated bamboo tie rod has been designed, one is the imitated bamboo without knots, the other is added knots. The three-dimensional modeling is carried out. The static analysis of finite element is carried out under the same working condition, and the stress nephogram and the position of the maximum value are obtained. The results of two kinds of simulated bamboo tie rod and cross-type tie rod are compared and analyzed. The results show that the mechanical properties of the whole simulated bamboo tie rod are superior to the cross-type tie rod.
Research on Anti-Vibration based on Screw Fixation and Friction-Assisted Fixation Method for the Space Payloads
Authors: Wang F F , Zhang L , Qiao Z H , Li L , Wang D K
Published: June 2020

Rack is kind of the experimental platform that used in the space station for performing scientific experiment. Many payloads are mounted on Rack with limited operating space. The shipment of a Rack to its final destination in orbit is far more complicated than for all other commercial products. The launch vehicle-induced vibration and shock environment can be a payload killer. Based on the limited operating space, this paper proposes a screw fixation and friction-assisted fixation method. Through establishing the force and the parameters of the screw fixation and friction-assisted fixation based on the payload, deriving the mathematical model and carrying out the dynamic environment test. Test results match theoretical results quite well. The screw fixation and friction-assisted fixation method can effectively resist excessive dynamic and shock loads.
Fluid-structure Interaction Characteristics of Spin-on Fairing Structure of Aerodynamic Simulation Static Load
Authors: Liu Longbin , Yang Songyuan , Jiang Zhenyu
Published: June 2020

With the rapid increase of aircraft speed, the impact of aerodynamic load on the aircraft is more significant, and aerodynamic load will cause the severe deformation of the structure, which will in turn affect the change of aerodynamic load. This paper takes a typical spin-on fairing structure as the study object with the finite element method, using simulated aerodynamic static load to study the effect of aerodynamic pressure on the load and deformation of the spin body structure, which could provide an effective method for the dynamic characteristics of the spin-on body structure, and for the study of aerodynamic load as well. And the results could also provide the initial finite element calculation data support for the damage evolution characteristics of fluid-solid coupling and long-term interaction of spinon fairing structures.
Data Exchange of Digital Twins Based on AML in Space Science Experiment Equipment
Authors: Guqi Peng , Hongen Zhong
Published: June 2020

With the development of Computer Aided Design(CAD) and manufacturing technology, various industries are transforming to digitalization, and the realization of the digital model of aerospace products is an important part of “digital aerospace”. Based on the theory of system engineering, this paper proposes a three-dimensional conceptual model of analysis of payload in the life-cycle of physical device design, as well as the concept of digital twin five-dimensional model in the design stage. Combined with the actual application requirements, this paper explores the content and standards of digital twin model construction of payloads, by using the model mapped to the AutomationML(AML) to realize the data exchange and fusion.
Self-healing performance of intelligently building concrete module
Authors: Zhang J X
Published: June 2020

Intelligent building concrete module is an important part of parametric construction and its self-repairing performance is the premise condition for ensuring the quality of the building. In this paper, some experiments have been done using fly ask, slag, meta-kaolin and silica fume mixed into cement in order to test several performances, including compressive performance, impermeability and self-healing performance. The results demonstrate: the worst healing effect was fly ash, followed by slag, meta-kaolin and silica fume. In the cement-based materials, the self-repair of the cracks mainly concentrated in the early production of cracks, so paid attention to the protection of the early maintenance is the key for self-repair effect.
Evaluation of dew point corrosion in acid atmosphere by wire beam electrode
Authors: Zhao Bo , Yu Yuxin , Guo Jing , Zhou Tianyu , Zou Shiwen , Xu Tong
Published: June 2020

In this article, wire beam electrode (WBE) was used to evaluate the corrosion behavior of ND steel in environmental acid atmosphere with different partial pressure of CO2. Meanwhile, corrosion products and surface morphology analysis also used to support this research. The results showed that the corrosion behavior began from the edge of droplet in dew point corrosion, and gradually spread to the center of it. The spread speed would increasing with CO2 partial pressure enhance, which was 24h in 5% CO2 and 4h in 50% CO2. Corrosion current density in the edge of droplet can form the “cathode-anode-cathode ring" structure, and disappears gradually as the corrosion time was going. Corrosion morphology observation results showed three ring shapes region and different elemental composition of different corrosion products, which is correspondence with the "cathode-anodWe-cathode ring" structure measured in WBE experiments. The results showed that the reaction gradually transferred to the uniform corrosion on electrode surface when the dew point corrosion reaction reaching the late stage. It comes from the dissolution, diffusion and reaction of gaseous corrosion medium of CO2 and O2.
Influence of solution temperature on microstructure and mechanical properties of wrought Al-Si-Mg alloy
Authors: Liu F , Gao F , Yu F X , Zhao D Z
Published: June 2020

The microstructure and mechanical properties of wrought Al-12.7Si-0.7Mg alloy were investigated aiming at understanding the influence of the solution treatmen. The result show that the Si particles were gradually rounded and the grain size increase with increasing the solution temperature from 500°C to 540°C. The alloy in T4 condition changed due to the grain szie, Si particles and the super saturation level of Mg ans Si solute atoms. With higher solution temperature, the volume fraction of the pricipitate becomes more which result in good manchannical properties.
Evolution of microstructure and toughness of very tough ferritic stainless steels
Authors: Gao F , Liu F , Fang C S , Zhang W , Zhang J J , Zou Y
Published: June 2020

In present work, the hot rolling with different finish rolling temperatures and annealing with different annealing temperature are employed with high toughness AISI444 ferritic stainless steel, and different microstructure are generated. It was indicated that low finish rolling temperature could lead to the significant refinement of the rolled and annealed microstructures and decrease the fraction of grains with {001} planes which are parallel to notch plane in the annealed microstructure. Therefore, the ductile-brittle transition temperature was lowered from -44.2°C to -48.8°C, resulting in the improvement of toughness after employing the low finish rolling temperature for ferritic stainless steel. When high annealing temperature can be applied, the coarsening of annealed microstructure occurred, but the fraction of grains with {001} planes which are parallel to notch plane in the recrystallized microstructure decreased. Thus, the ductile-brittle transition temperature has no significant change after annealing with different temperatures.
A Preliminary Study of a Graphene Fractal Sierpinski Antenna
Authors: Boretti Alberto , Rosa Lorenzo , Blackledge Jonathan , Castelletto Stefania
Published: June 2020

We provide a preliminary study of a Graphene fractal antenna operating at THz frequencies with the opportunity to modulate the emission. There are many advantages of the fractal design, namely multiband/wideband ability, and, a smaller, lighter and simpler configuration for higher gain, that can benefit from the coupling with Graphene, the thinnest and strongest of materials exhibiting very high electrical conductivity and tunability. This paper proposes a conceptual background for the study and presents some preliminary results on the electromagnetic emission simulations undertaken.
Mechanical and Thermal Behaviour of Epoxy/Hexagonal Boron Nitride/Short Sisal Fiber Hybrid Composites
Authors: Agrawal Alok , Chandrakar Saurabh , Sharma Abhishek
Published: June 2020

Hybrid composite i.e. surface modified hexagonal boron nitride (hBN) and short sisal fiber reinforced in epoxy matrix is fabricated using hand lay-up method. The effect of surface modified hBN filler and sisal fiber content on mechanical and thermal properties of epoxy based hybrid composites were investigated in this paper. The main aim of the investigation is to develop a material which can found its application in microelectronic components. As per the requirement of microelectronic industry, the material should possess high thermal conductivity. Hence, thermal conductivity of epoxy increases with increase in hexagonal boron nitride content. Inspite of insulative nature of sisal fiber, the study shows that its inclusion in combination with hBN enhances the thermal conductivity if the content of both the fillers were properly selected. Other thermal property like coefficient of thermal expansion and glass transition temperature appreciably improves when combination of fillers were added in epoxy matrix. Mechanical properties under study i.e. tensile strength and compressive strength also enhances when combination of sisal fiber and hBN were incorporated as compared to when single filler hBN were used. Hence, usage of hybrid filler as reinforcement in epoxy improve overall mechanical and thermal property of the developed material.
Morphological and Mechanical Properties of Natural Rubber Compound/Poly(butylene succinate) Blend
Authors: Prasoetsopha N , Thainoi P , Jinnavat R , Charerntanom W , Hasook A , Singsang W
Published: June 2020

Biodegradable poly(butylene succinate) (PBS)/natural rubber compound (NRC) blend was melt mixed using a two-roll mill. A weight ratio of PBS/NRC was 100/0, 90/10, 80/20, 70/30, 60/40 and 50/50. Morphological and mechanical properties were investigated. The results showed that the elongation at break increased with an increase of NRC content until the ratio of 80/20. While the tensile strength continuously decreased with an increasing amount of NRC. Moreover, the impact strength of the PBS/NRC blend increased until the ratio of 80/20 and tended to decrease in the further ratios. Morphology of PBS/NRC blend showed that NRC had good dispersion in PBS matrix up to 80/20. When the amount of NRC was increased, it became a larger particle due to an agglomeration, resulting in the mechanical properties.
Study on the Influence of Blast Furnace Slag on Chloride Ion Penetration Property
Authors: Subpa-asa P , Ken K , Satoshi F , Shigeyuki D
Published: June 2020

Sustainability is becoming more and more important, which is why the concrete and cement industry are attempting to reduce negative impacts to the environment. One of the methods regarding this is to use industry by-products from the manufacturing of steel products like blast furnace slag (BFS) to replace the raw materials required in cement. The chloride ion penetration has to also be taken into consideration since it reinforces the concrete structure. Thus, the influence of BFS on blocking resistance and chloride ion penetration by using BFS with different Blaine value is studied by using “Standard on Test Methods for Chloride Ion Diffusion Coefficients in Concrete” by electrophoresis (Draft) (JSCE-G571-2003)” and the total chloride ion amount was measured in accordance to JIS R 5202. The result is that using BFS in cement has influences on the penetration properties.
Utilization of Waste Lubricating Oil as a Diesel Engine Fuel
Authors: Sharma Abhishek , Gupta Gaurav , Agrawal Alok
Published: June 2020

This research work is focused on the regeneration of used lubricating oils which are simply thrown out to the environment. It is evident from the past research outcome that there is an acute shortage of petroleum oils and regeneration of fuels from used lubricating oils can be potential substitute of fossil fuels. But due to some drawback such as higher viscosity and density it cannot be used as a single fuel. In this regard the distillation of used lubricating oil has been carried out with. Further, this distilled used lubricating oil (DULO) was blended in different proportions with Jatropha biodiesel (JB) which has excess oxygen by about 10%. The aim of the current study is to investigate the performance and emission characteristics of a DI diesel engine run on these blends and comparison with base fuel diesel. The behavior of the engine was evaluated in terms of brake thermal efficiency, brake specific fuel consumption, exhaust gas temperature, carbon monoxide emission, hydrocarbon, nitric oxide emission and smoke opacity. The test result revealed that, the behaviour of the engine run on the JBDULO20 (i.e. 80% JB and 20% DULO) blend was better than other blends considered in the study.
Effects of plasma treatment on properties of carbon fiber and its reinforced resin composites
Authors: Kong Lingmei , Wang Xiaobing , Zheng Wei , Tian Shiwei , Qi Yanyan , Xue Yajuan , Wang Baochun
Published: June 2020

The influence of plasma treatment on the wettability of carbon fiber was studied using the vacuum assisted resin transfer molding (VARTM) process. The influence of plasma treatment on the mechanical properties of carbon fiber-reinforced polymer (CFRP) composites, including interlaminar shear strength and tensile properties, were investigated. The carbon fiber surface chemistry analysis was carried out by Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). Results showed that low-temperature plasma treatment had little effect on the surface morphology of the carbon fiber; however, it changed the chemical surface state of the carbon fiber, which contributed to enhance the wettability of the carbon fiber by increasing the perfusion speed of the resin to be more than two times of the original speed. The fiber wettability improvements are of great significance to the preparation of the CFRP composite by the VARTM process. Compared to untreated carbon fiber, the plasma treatment caused an acceptable decrease in tensile properties and offered an increase in the interlaminar shear strength of the CFRP composite. Low-temperature plasma treatment played an important role in the effective preparation and application of the CFRP composite.
0-Concordance of 2-knots
Authors: Sunukjian Nathan
Published: June 2020

In this paper we investigate the 0-concordance classes of 2-knots in

S
4

S^4

, an equivalence relation that is related to understanding smooth structures on 4-manifolds. Using Rochlin’s invariant, and invariants arising from Heegaard–Floer homology, we will prove that there are infinitely many 0-concordance classes of 2-knots.
A steady length function for Ricci flows
Authors: Jordan Joshua
Published: June 2020

A fundamental step in the analysis of singularities of Ricci flow was the discovery by Perelman of a monotonic volume quantity which detected shrinking solitons. A similar quantity was found by Feldman, Ilmanen, and Ni [J. Geom. Anal. 15 (2005), pp. 49–62] which detected expanding solitons. The current work introduces a modified length functional as a first step towards a steady soliton monotonicity formula. This length functional generates a distance function in the usual way which is shown to satisfy several differential inequalities which saturate precisely on manifolds satisfying a modification of the steady soliton equation.
The Kohn-Laplace equation on abstract CR manifolds: Global regularity
Authors: Khanh Tran , Raich Andrew
Published: June 2020

Let

M
M

be a compact, pseudoconvex-oriented,

(
2
n
+
1
)

(2n+1)

-dimensional, abstract CR manifold of hypersurface type,

n
≥
2

n\geq 2

. We prove the following:

(i) If

M
M

admits a strictly CR-plurisubharmonic function on

(
0
,

q
0

)

(0,q_0)

-forms, then the complex Green operator

G
q

G_q

exists and is continuous on

L

0
,
q

2

(
M
)

L^2_{0,q}(M)

for degrees

q
0

≤
q
≤
n
−

q
0

q_0\le q\le n-q_0

. In the case that

q
0

=
1

q_0=1

, we also establish continuity for

G
0

G_0

and

G
n

G_n

. Additionally, the

∂
¯

b

\bar {\partial }_{b}

-equation on

M
M

can be solved in

C
∞

(
M
)

C^\infty (M)

.

(ii) If

M
M

satisfies “a weak compactness property” on

(
0
,

q
0

)

(0,q_0)

-forms, then

G
q

G_q

is a continuous operator on

H

0
,
q

s

(
M
)

H^s_{0,q}(M)

and is therefore globally regular on

M
M

for degrees

q
0

≤
q
≤
n
−

q
0

q_0\le q\le n-q_0

; and also for the top degrees

q
=
0

q=0

and

q
=
n

q=n

in the case

q
0

=
1

q_0=1

.

We also introduce the notion of a “plurisubharmonic CR manifold” and show that it generalizes the notion of “plurisubharmonic defining function” for a domain in

C

N

\mathbb {C}^N

and implies that

M
M

satisfies the weak compactness property.
Preventative strategies and interventions to improve outcomes during heatwaves
Authors: Brennan Michelle , O’Shea Paula M , Mulkerrin Eamon C
Published: June 2020

Extreme weather events including recently experienced prolonged heatwaves are predicted to increase in frequency and intensity as a result of climate change. Vulnerable groups, and particularly older persons, are at increased risk of heat-related illness and mortality. Multimodal interventions that incorporate community, primary and secondary care programmes are required. Social programmes such as early warning systems, regional heat plans and community-led initiatives that specifically target the isolated, dependent older person are protective. Establishing clear and effective communication on health promotion and preventative measures is the key. Energy-efficient building design and eco-city planning are vital to reduce the impact of heatwaves at both a population and individual level. Anticipatory strategies should be adopted to ensure ample access to fluids, target barriers to increase oral intake and allow early identification of intercurrent illness, along with regular medication reviews. Prompt management of risk factors for the development of heat-related illness and treatment of complications such as heat stroke and cardiovascular events are keys to reducing the negative health impact of extreme heat in at-risk populations. Morbidity and mortality in heatwaves should be preventable. Evidence-based interventions are available to mitigate and prevent the negative health impact of extreme heat and should be implemented in all residential settings.
Acceptability and Usability of Computerized Cognitive Assessment Among Australian Indigenous Residents of the Torres Strait Islands
Authors: Thompson Fintan , Cysique Lucette A , Harriss Linton R , Taylor Sean , Savage Greg , Maruff Paul , Mcdermott Robyn
Published: June 2020

Objectives

This cross-sectional study aimed to investigate the acceptability and usability of the Cogstate Brief Battery (CBB) in a community-based sample of Australian Indigenous people from the Torres Strait region, based on a user experience framework of human–computer interaction.

Methods

Two-hundred community participants completed the four subtests of the CBB on an iPad platform, during a free adult health check on two islands in the region, between October and December 2016. Acceptability was defined as completing the learning trial of a task and usability as continuing a task through to completion, determined by examiner acumen and internal Cogstate completion and integrity criteria. These were combined into a single dichotomous completion measure for logistic regression analyses. Performance—measured as reaction times and accuracy of responses—was analyzed using linear regression analyses.

Results

CBB completion ranged from 82.0% to 91.5% across the four tasks and the odds of completing decreased with age. After adjusting for age, iPad/tablet familiarity increased the odds of completion for all tasks while level of education and employment increased the odds for some tasks only. These variables accounted for 18.0%–23.8% of the variance in reaction times on speeded tasks. Age and education had the most effect, although semipartial correlations were modest.

Conclusions

When administered in a health-screening context, the acceptability and usability of the CBB were greatest in young- to middle-aged participants with some education and iPad/tablet experience. Older and more vulnerable participants may have benefited from additional time and practice on the CBB prior to administration.