bluuebunny/crossref_metadata_2025 huggingface dataset:
The lithofacies superposition patterns of oil-bearing reservoir of different productivity levels of the Lower Fourth Member of Eocene Shahejie Formation in Dongying Sag, Bohai Bay Basin
Authors: Xu Ningning
Published: May 2021

Based on core observation and well logs, the paper reveals the lithofacies superposition patterns of oil-bearing reservoir of different productivity levels of the Lower Fourth Member of Eocene Shahejie Formation in Dongying Sag, Shengli Oilfield. The reservoir is divided to three types according to its productivity levels. Type A: natural productivity > 10 tons per day; Type B: 5 tons per day <natural productivity ≤10 tons per day and Type C: natural productivity ≤5 tons per day. Their corresponding lithofacies superposition patters are “thin bedded sandstone + mudstone superposition model”, “multi-stage superposition of thick-bedded conglomerate and pebbled sandstone” and “superposition of medium thick pebbled sandstone, coarse-grained sandstone and medium-grained sandstone”.
Analysis of influence of coal mining on stability of tower on Loess Slope and deformation monitoring
Authors: Feng Huang , Wang Kedong , Yue Yingmin , Hu Pengfei
Published: May 2021

A three-dimensional geological model of Goaf is established, and the finite element analysis of Goaf deformation is carried out by using the analysis module of construction stage in Midas/GTS 2.6. The stability of the tower is demonstrated with the deformation monitoring results, and the estimated cost of route modification is saved, the optimized route has accumulated experience for transmission line engineering construction in Goaf.
Investigation Study on the Living Environment of Rural Mountainous in Eastern Zhejiang
Authors: Liu Fei , Yang Zhong , Wang Ruifeng
Published: May 2021

In this paper, the living environment of eural mountainous in eastern Zhejiang were investigated. 76 geological hazards in this areas were selected as the investigation objects. The investigate results were showed that landslides, collapses and debris flows will effect the residents living. There were 43 instable disasters in the investigation areas; and 1 largest size, 41 medium size and 34 small size disasters. The risk evaluation results were showed that there were 16 high risk and 60 medium risk of disasters in this areas. The research results will provide a basis for the disaster prevention and help the residents to avoid the disasters.
Study on the construction strategy of South Taihu Lake New District under the concept of ecological civilization
Authors: Zhang Hua , Zhang Niyan , Xiong Minghui , Yao Kangkang , Qian Yao
Published: May 2021

With the constantly advancing of urbanization in our country, new urban districts are constantly emerging. High intensity development and construction not only caused a large amount of resource consumption, but also has brought many ecological problems. Therefore, the construction of new urban districts must pay attention to the construction of ecological civilization. Taking the new district of the southern Taihu Lake in Huzhou as an example, this paper combed the contents and the methods of the planning and construction about new urban districts in the concept of ecological civilization. On the basis of the analysis of the current situation, the paper proposes the construction strategy of the southern Taihu Lake from four aspects, such as the high level of design, high standard of control, high-tech innovation and high strength of safeguard, in order to provide some revelations for follow-up construction of the new district.
Influence of Freeze-thaw Cycles on Water Content Properties of Silty Clay in Xuchang
Authors: Wang Jing , Liu Yanling , Tang Dongqi
Published: May 2021

Silty clay is the main structural stratum in Xuchang area. Based on the freeze-thaw cycle test, the influence of freeze-thaw on the water content and void ratio of silty clay is analyzed. The test results show that in the case of no recharge water source, the freeze-thaw cycle will cause water migration in the soil body, which will produce local high water content zone on the surface, and cause water loss and water content reduction, which is easy to cause soil loss Water shrinkage produces cracks. The results show that the higher the initial water content is, the faster the water content will be lost, and the different initial water content will tend to be the same when the freeze-thaw cycle reaches more than 15 times. With the increase of freeze-thaw times (5 times), the void ratio tends to be stable. The change of soil properties caused by water migration under freeze-thaw cycle plays an important role in soil stability control. The research results of this paper are helpful to carry out scientific and reasonable engineering prevention measures and provide basic data.
Application of Architectural Decoration Materials to Space Design of Rehabilitation Center for Autistic Children
Authors: Zou Shuzhen , Chen Fangting
Published: May 2021

Architectural decoration materials play an irreplaceable role in indoor design, landscape design and decoration design. A suitable decoration material can elevate the aesthetics and comfort of the overall space. There are numerous cases of ecological protection and aesthetic comfort achieved through rational use of architectural decoration materials in contemporary Chinese design; however, the indoor space design of rehabilitation center for autistic children is still out of step. This paper is to discuss the architectural decoration materials suitable for children’s rehabilitation from the perspective of particularity of autistic children, in order to provide a design blueprint for creating a safe and comfortable indoor space for autistic children, maximizing the treatment effect and improving their abnormal behaviors as well.
Analysis on the Mechanism of the Heavy Snow Process in the Northeast of Tarim Basin, Xinjiang, in 2018
Authors: Chen Yanli , Qin Rong , Pan Cunliang , Jiang Aihong , Su Junfeng
Published: May 2021

An analysis was made on the routine data of meteorological stations, high-resolution satellite cloud images and the NCEP/NCA R 1°×1° reanalysis data during one instance of heavy snow precipitation that took place in northern Bazhou, Xinjiang on October 18, 2018, followed by a diagnostic analysis of physical quantities, including the large-scale circulation anomalies, upper and lower-level circulation conditions and water vapor transport. The following are the results: (1) the heavy snow precipitation process in northern Bazhou, Xinjiang is a heavy precipitation process largely caused by a convergence of severely cold air carried from Siberia by an upper vortex, and a strong, warm and humid air current from southwest China. During this weather process, the upper layer was dry and cold, while the lower layer was warm and humid; an obvious wind shear and convergence center appeared at 700hPa, 850hPa in the lower layer over northern Bazhou; the heavy precipitation area was located in the front of the trough bottom at 500hPa, on the left side of the lower-level shear line. 2) The secondary circulation formed on the right side of the upper-level jet stream entrance area at 200hpa and 300hpa enlarged the ascending motion of the heavy snowfall area, while the low-level easterly jet stream played a critical role in transporting and accumulating water vapor at 850hpa. 3) The variations of temperature at 850hpa and on the ground layer were of certain indicative significance to the forecast of the precipitation phase state, and the temperature field at 850hpa well-indicated the change from rain to snow. When the air temperature fell to 0.5°C or so, and the ground temperature fell below 0°C given T700hpa<-10°C and T850hpa<-2°C, it could be used as a criterion for the judgment of rain changing to snow. 4) The vapor condition, lifting force condition and unstable stratification condition in the numerically-forecasted physical quantity field, all had a good guiding effect on the heavy precipitation process that took place in the Yanqi Reclamation Area.
Awareness of construction professionals from the Northern Region of Malaysia about low carbon building materials
Authors: Omar M R , Ayob A , Ibrahim S , Rahim M Abdul , Rani H A , Mokhtar H , Leman A M , Zakaria M H
Published: May 2021

Despite current global market conditions, a superior financial climate has lowered the demand for innovative low carbon building materials, with construction owners typically prioritizing project value, time, practicality, and aesthetics. This situation creates an obvious dilemma for practitioners and stakeholders, as carbon emission linked to the use of construction materials should decrease. This study presents the awareness among the construction professional in the northern states of Malaysia in relation to low carbon building materials (LCBM) via interviews and structured questionnaire surveys conducted with 93 companies of architects and civil and structural consultants. Of 76.9% valid responses, 44.6% to 51.4% claimed to be “Aware and have a good knowledge” about unfired earth bricks, prefabricated hollowcore floor system (PHFS), and prefabricated timber frame system; however, their usage remained low. PHFS provided satisfactory experiences to practitioners and ranked the highest (20.3%) in the recommendations for future projects. The sustainability and suitability of a particular LCBM is highly determined on-site, has project specific influences, and varies across structures types from project to project.
A review: Study on waste rubber as construction material
Authors: Mutalib N A N A , Mokhatar S N , Budiea A M A , Jaini Z M , Kamarudin A F , Noh M S Md
Published: May 2021

Sustainable construction is highlighted in current development as the environmental issue is one of the major issues of global concern. This issue also relates to waste generated each year. The bulk of waste was estimated to increase, which can reduce space in the world and can cause pollution. Many researchers have come up with inventions and ideas to manage that situation. Some researchers use the waste rubber in a concrete mix as a partial coarse or fine aggregate replacement. The alternative in a concrete mix depends on the size of the rubber that is used and the appropriateness. In this paper, the critical perspective of waste rubbers discussed in detail. It is shown from the review that if compared with the existing one, there is some reduction in the workability and mechanical properties of concrete. Rubberised concrete, however, still has its superiority in terms of energy absorption. The use of pozzolanic material in the concrete mix, the application, the proportion of rubber and the choice of rubber types helps a lot to compensate for the weakness of rubberised concrete.
Recycled Glass Cullet as Fine Aggregate and Partial Cement Replacement in Concrete
Authors: Duraman S B , Li Q
Published: May 2021

Utilisation of recycled glass cullet in concrete has obvious benefits with respect to environmental conservation and sustainable development. The problems of rising landfills can be reduced. Reduction of primary aggregates for concrete where alternative materials would suffice can also be fulfilled. Glass also contains large amounts of silicon and calcium which means that in theory, is pozzolanic. However, the possibility of alkali-silica reaction (ASR) due to the presence of silica must also be addressed. Tests were performed to investigate the suitability of using cullet in concrete. A sieve analysis was performed to determine the size distribution of the cullet and provided basis to the range of samples that could be cast. Using cullet as partial replacement aggregate in concrete has resulted in minor increases in concrete consistence (workability) and minor reductions in compressive strength. When ground glass cullet (GGC) was used as 30% partial cement replacement, the consistence increased considerably, whilst the later age compressive strength was close or higher (depending on the mix proportions used) compared to the corresponding control mixes, which did not have GGC incorporation. The early age strength was lower and strength development was slower at early ages further suggesting likelihood of pozzolanic activity. Accelerated ASR tests have shown the occurrence of ASR in concrete mixes using cullet as replacement aggregate to be more than control mixes which used conventional aggregate. The magnitude of ASR was also found to be colour dependant-green coloured cullet resulted in less expansion than when using amber cullet. Qualitative microstructural analysis of specimen micrographs recorded in Secondary Electron Imaging (SEI) mode using a Scanning Electron Microscope (SEM) have shown that mortar specimens using cullet displayed more cracking at longer curing periods. Cracks propagated from, and surrounded the glass particles, further suggesting the occurrence of ASR activity. Depending on size classification used, glass cullet can therefore be recommended to be used as partial aggregate replacement and partial cement replacement in concrete. The possibility of durability attack due to ASR reaction must however be taken into consideration.
Performance of fly ash and silica fume self-compacting concrete filled steel tube stub columns under axial compression
Authors: Mustapha Falmata Audu , Sulaiman Arizu , Mohamed Roslli Noor
Published: May 2021

Experimental research on the performance of fly ash and silica fume selfcompacting concrete filled steel tube (FSS CFST) stub columns under axial compression were conducted. The main parameters varied in the tests are steel tube’s diameter to thickness ratio, D/t (from 20 to 33), and yield strength (from 275.83 MPa to 350.51 MPa). The self-compacting concrete grade used as infill is M60 concrete with 50% and 10% addition of fly ash and silica fume, as partial replacement of Portland cement. The performance of FSS CFST stub columns is examined via the axial compression capacity, load-shortening response, and mode of failure of 12 specimens. The results indicate that the ultimate axial load capacity of the columns increases as the D/t ratio decreases. The FSS CFST columns have a maximum concrete contribution ratio of 3.72, a strength index greater than unity, and a ductility index of 2.431 and below. The predicted values obtained using Eurocode 4 closely estimate the test results with a mean of 0.927 and a standard deviation of 0.073. Conversely, the predicted values using ACI code are more conservative with a mean of 1.341 and a standard deviation of 0.089.
Seismic performance of low-rise building using graded concrete as flexural elements
Authors: Prayuda H , Pratama M M A , Novitasari Y , Damayanthi W , Arifurrizal S , Puspitasari P , Permanasari A A
Published: May 2021

Graded concrete is a material innovation in the field of civil engineering that aims to create environmentally friendly and economical construction materials. Previous research has shown that graded concrete increases material rigidity so that graded concrete can increase the level of serviceability of structures, indicated by the decreasing of deflection. Investigations on the performance of structures using graded concrete as building material need to be studied further with broader structural indicators. Further studies related to structural performance including base shear reactions, fundamental periods, storey stiffness, storey drift, and storey displacement, should also be discussed. In this study, a 3-storey residential building is modelled using ETABS in 3D approach. The effect of disparity in concrete strength on structural performance is examined. The buildings that employ graded concrete as a construction material can offer a better level of occupant comfort due to the lesser vibration period generated. The application of graded concrete in beam components can increase the value of the storey stiffness. It is because of the greater the modulus of elasticity, the greater the stiffness produced by the beam. It increases the confinement of the enclosed plate so that the stiffness of the building floor also increases. The use of high strength concrete in the beams will change the mode shape of the structure from flexure to shear type. In shear mode shape, the column will form a double curvature so that the mode shape of the structure tends to form a convex pattern. The benefit of the shear-type mode shape is the lesser value of storey displacement at the top level.
Structural Performance of Lightweight Foamed Concrete Slab Strengthening with Fibres: A Review
Authors: Mohamad Noridah , Lakhiar Muhammad Tahir , Yap Wei Xian , Samad Abdul Aziz Abdul , Muthusamy Khairunisa
Published: May 2021

Light weight foam concrete (LWFC) has a density between 400 kg/m3 to 1600 kg/m3 and has a minimum of 20% entrapped air in volume. The utilization of LWFC makes the building structure light and durable. Fibres can be used as reinforcement in LWFC to increase its structural behaviour in terms of strength and cracking pattern. This paper presents the potential review on the structural behaviour of LWFC consisting fibres. From literature reviews it can be seen that great number of researches used the fibres such as coir, Polyethylene terephthalate (PET), polypropylene (PP), steel, and glass fibres in LWFC. The mechanical and structural properties of LWFC slab were reviewed. From the previous studies it was concluded that LWFC 0.6 % glass fibre, 0.4 % hybrid steel fibre and 0.3 % of coir fibre were optimum where LWFC had high mechanical and structural behaviour of LWFC slab compare to control sample.
Strength Capacity of Concrete Using Micro Steel Fiber: A Review
Authors: Manaf A F A , Shahidan S , Mazlan M F N , Ramasamy S , Zuki S S M , Azmi M A M , Ali N , Ibrahim M. H Wan , Rahim M Abdul
Published: May 2021

Concrete is widely used in the engineering field, particularly in construction. Despite its widespread use in the construction industry, concrete is brittle and has a number of drawbacks, including low tension and crack resistance. As a result, many researchers discovered a way to enhance concrete ductility through adding micro steel fibers (MSF) as a reinforcement. This study explores the impact of MSF on slump height, and the toughness of various concrete. To obtain relevant paper for this research, a systematic literature review was used. When 0.5% to 2% MSF were present in the concrete composite, the result shows a positive increment on its strengths. Meanwhile, the toughness impact of self-compacting concrete (SCC) is reduced depending on what type of water used during the mixing process. Aside from that, adding 0.5% to 2% MSF increases the tensile strength of SCC and ultra-high performance concrete (UHPC). Ultimately, incorporating MSF with concrete to increase the durability is a great idea.
Optimum mix design of high-performance concrete containing micro POFA using historical data design
Authors: Hassan Wan Nur Firdaus Wan , Ismail Mohamed A , Ismail Mohammad , Hussin Mohd Warid , Rahman Muhammad Ekhlasur , Padil Khairul H , Darus Nadirah
Published: May 2021

This paper presents the optimized mix design based on the response surface methodology (RSM) in producing high performance concrete (HPC) by utilizing palm oil fuel ash (POFA) as cement replacement material. The historical data design was used based on the existing testing data determined from the laboratory experiments. The variable in this study includes POFA percentage (10%, 20%, and 30%). The concrete mixes were tested both for fresh and hardened properties of high performance concrete. The optimized level for POFA in the HPC mix proportion was determined by the maximization of workability, early, 28 days’, and later compressive strength. The response of each mix that contains POFA showed a significant increase in the workability and compressive strength with respect to the plain HPC. The results presented the optimum solution for mix design of high performance concrete with POFA that achieve the targeted goal performance criteria (fresh and hardened properties).
Indoor thermal comfort assessment in office buildings in hot-humid climate
Authors: Abass F , Ismail L H , Wahab I A , Mabrouk W A , Kabrein H
Published: May 2021

This paper aims to assess the user’s perception of thermal comfort and air conditioning in office buildings in Batu Pahat, Johor area. Field experiments were conducted utilizing environmental measurement and Post Occupancy Evaluation (POE) in Batu Pahat District Land Office (Pejabat Daerah) and (C2 and ORICC) office buildings in the Universiti Tun Hussien Onn Malaysia (UTHM). The environmental measurement was conducted using thermal comfort station BABUC A, whereas the POE was based on the ASHRAE 55-2010 standard. The environmental parameters included relative humidity, air temperature, and air velocity. They were measured and compared with MS-1525, ASHRAE 55, and ISO 7730 standards. Results indicated that indoor air temperature in C2 has good compliance with MS-1525, ASHRAE 55, and ISO 7730 standards and criteria with a measured comfort range of 24 °C-26 °C. Whereas for ORICC and Pejabat Daerah, temperatures were a bit lower than the suggested range. At the same time, the range of relative humidity was found to be higher than ASHRAE limits but complied with other standards. Moreover, adequate air velocity standards were not met in the three office buildings, in which they were measured within 0.4-0.5 m/s range. Furthermore, thermal comfort levels and the POE survey results indicated that users’ in hot tropical office buildings could acclimate to a higher indoor environment than what was suggested by standards.
Experimental study: Shear behaviour of reinforced concrete beams using steel plate strips as shear reinforcement
Authors: Eklou Remir J , Yani Muhammad B , Saifullah Halwan A , Sangadji Senot , Kristiawan Stefanus A
Published: May 2021

Stirrups bars are widely used as shear reinforcement in reinforced concrete beams. It is quite attractive to explore the use of another type of material for stirrups. This study aims to investigate the shear behaviour of reinforced concrete beams using steel plate strips and conventional stirrups as shear reinforcement. Two full-scale reinforced concrete beams were tested to fail in shear in this experimental program, and the test parameter for this study was the types of shear reinforcement. The shear resisting behaviour of the beam specimens was discussed by evaluating the crack patterns, load-deflection response and the shear strengths of the beam specimens. The shear capacities determined experimentally were compared with the prediction values calculated based on the Modified Truss Theory. The ratio of the measured to estimated shear strength in the steel plate RC beams and reference beam showed a fairly good agreement as these ratios were only slightly different. Results of this study show that there is only a slight difference in the global behaviour of the steel plate RC beam and the reference beam using conventional stirrups.
Betta persephone: The Challenges in Only Existed Natural Habitat; Ayer Hitam Peat Swamp Forest Reserve (AHPSFR) Muar Johor
Authors: Rafiq M Mohd , Nazirah M A , Adelyna M A Noor
Published: May 2021

Betta persephone is a native species and has been categorized as endangered in Ayer Hitam Peat Swamp Forest Reserve (AHPSFR), Muar Johor. This area is the only wild stronghold of this species. This species is facing greatest threats nowadays. As the study aimed to analyze the challenges of this species by using qualitative method. Interviews session has been conducted by the involvement of four respondents which all of them are ichthyologists and have expertises in this matter. Also, observations have been conducted inside AHPSFR. The data that have been gathered in interviews being analyzed by using NVivo software. For, observation sessions, a checklist was being obtained from the findings of the interview sessions. In the findings, all the respondents and observations have the consensus that challenges have been found out were overexploitation, land encroachment for oil palm plantation, illegal logging, water contamination, fires and illegal mining. The challenges that have been stated need to be bridle for the survivor and sustainability of the species for the reference of future generations.
Non-Flooding and Flooding Characteristics of a Natural Straight River
Authors: Rashid M F Abd , Ibrahim Z , Jumain M , Sa’ari R , Alias N , Jamal M H , Bakar A Abu
Published: May 2021

Floods happen when the flow of water exceeds the river banks and flow through the floodplain area, which is known as overbank flow. Flood causes damage to infrastructure and buildings and loss of life. Therefore, this paper investigates the characteristics of pattern river development; width, depth, and flow within the channel. This physical modelling discusses the pattern of the river by employing the current meter and point gauge equipment to collect and record the data along the channel. The discharge of 0.2 L/s and 0.5L/s were used for nonflooding and flooding cases. The non-flooding and flooding cases were identified by using a rectangular flume known as “Flexible Channel Flume”. The flume used in this study has 4.95 X 0.69 X 1.26 m of the rectangular main channel with a non-fixed-bed. As a result, the flooding case shows the depth of the channel increasing at the upstream and decreasing at the downstream compared to the non-flooding case with changes of velocity and manning’s roughness coefficient n.
Development of Water Quality Monitoring Device Using Arduino UNO
Authors: Hakimi I M , Jamil Z
Published: May 2021

Regular water quality monitoring of water bodies is essential to ensure it is within the allowing standard limits. The development of a simple and low-cost water quality measurement device for real time monitoring using Internet of Things (IoT) technology is presented in this study. Kolora meter is an alternative to the existing commercial monitoring devices. It was developed using the open-source platform Arduino UNO model and NodeMCU board as the microcontroller and Wi-Fi connection respectively. Two sensors such as temperature and turbidity were selected to be installed in the early stage of Kolora meter development. The physical parameters (temperature and turbidity) of water were measured and the measured data collected are able to be viewed and monitored on the mobile phone using Kolora Mobile Application via Wi-Fi connection. Therefore, this surface water quality device has potential to be applied in real time monitoring for early pollution detection and during COVID-19 pandemic spread due to limited movement.
Effects of Curing Time Using Crushed Coconut Shell (CCS) and Coconut Shell Ash (CSA) as Additive to Improve Lateritic Soils
Authors: Ramli R , Mansor N A Wan , Idrus J , Mansor S , Abdullah N H H
Published: May 2021

Numerous constructions in Malaysia have encountered the issues where soil cannot fulfil the standard required specification due to the bearing capacity of soft soil is too weak to withstand traffic loading. Recently, there is a lot of defeats related to soil settlement and distorting of the structure effect by the inflated compressibility and low in shear strength of the soil. This research study on the effects of natural additives in crushed coconut shell (CCS) and coconut shell ash (CSA) to enhance the durability of lateritic soil for road pavement. The effects of curing time in the CCS and CSA admixture of soil is examined. Different proportions of 5% and 9% CSA with a constant 8% CCS were used to study the effect on lateritic soil. Series of preliminary tests were performed followed by engineering test of Compaction test in identification on optimum moisture content (OMC) and maximum dry density (MDD) followed by California Bearing Ratio (CBR) for curing day of 4 days, 7 days and 14 days of soil mixtures sample to investigate its enhancement to soil strength. Further review from the previous research has also been carried out and it is pointed out that by using natural CCS and CSA brushed up the soil load-bearing capacity due to the increment of CBR value obtained as compared to the normal mix. Hence, it can be concluded that the combination of natural additives CCS and CSA in the soil also have the capability to improve the soil strength and can be suggest to replace aggregates and cement for use in lateritic soil stabilization subject to road works.
Traffic Congestion Evaluation at the Unsymmetrical Signalized Intersection of Sentul, Yogyakarta
Authors: Mahmudah N , Anjasmoro B S , Muchlisin M
Published: May 2021

Sentul intersection is the unsymmetrical signalized intersection located nearby the Sentul Market of Yogyakarta, which has a potential causing traffic congestion. The study aims to analyze the performance of an unsymmetrical intersection based on Indonesian’s regulation and to determine the congestion cost occurred at the Sentul signalized intersection. This study utilizes a quantitative method to evaluate the intersection performance by considering delay, vehicle queue, congestion cost, and level of service (LOS). The study included primary data collection from a traffic survey, a traffic modelling to assess the intersection performance, and a congestion cost analysis using software by considering three different conditions: Existing Condition, Alternative 1 and Alternative 2. The results showed that the performance of the existing condition was very poor with average delay of 106.71 second/vehicle, queue time of 134.42 seconds, LOS of F, and congestion cost of intersection was IDR 3,722,627 per hour. The 1st alternative was re-designing phase time of traffic light and the 2nd alternative involved re-designing green time, widening of approach area, applying left turn on red (LTOR) for the west-arm of intersection, and removing on-street parking area. The 2nd alternative is the best solution since it will reduce delay by 30 %, vehicle queue by 54 %, congestion cost decrease by 50 %, the LOS increase from F to E, and then improve intersection performance significantly.
Electrodeposition of FeCrNi and FeCr alloys and influence of heat treatment on microstructure and composition
Authors: Meinhold V , Höhlich D , Dittes A , Mehner T , Lampke T
Published: May 2021

The electroplating of iron-chromium and iron-nickel-chromium layers is an economic alternative to mild steel and hard-chrome layers from chromium (VI) electrolytes. Iron-chromium and iron-nickel-chromium layers were electrodeposited using an environment friendly chromium (III) electrolyte. The layers were heat-treated at different temperatures (150 °C, 300 °C, 450 °C and 600 °C) in order to determine the temperature at which recrystallization takes place, which phases are formed and to study the influence on the element content. The phase analysis was conducted by X-ray diffraction, the chemical composition and the microstructure were characterized by the scanning electron microscopy. Both layer systems show an X-ray-amorphous structure that begins to recrystallize at a temperature of 450 °C. From a heat-treatment temperature of 600 °C, the organic additives decompose and the oxygen forms chromium oxide with the chromium.
Electrolyte design and characterization of REACh-compliant Zn-W and Zn-W-Cu electrodeposits
Authors: Morgenstern R , Müller M , Höhlich D , Mehner T , Lampke T
Published: May 2021

Within this work, an entirely new electrolyte system for the electrochemical deposition of REACh-compliant Zn-W and Zn-W-Cu alloy layers was developed based on thermodynamic calculations. The required constants of complex formation were determined using potentiometric titrations. The layers were analyzed with regard to the layer microstructure (including coating thickness, chemical and phase composition), the optical properties (including gloss and color) and the passivation and corrosion behaviors. The Zn, Zn-W, and Zn-W-Cu layers are characterized by a decorative appearance, high uniformity, a nanocrystalline structure and natural passivation during the exposure in the climate chamber. Due to their particularly favorable optical properties and their pronounced natural passivation, the Zn-W alloy layers exhibit a great potential for industrial applications.
Conversion layers by plasma-electrolytic oxidation of aluminum in acrylate and benzoate electrolytes
Authors: Morgenstern R , Selyshchev O , Mehner T , Lampke T , Zahn D R T , Goedel W A , Schreckenbach J
Published: May 2021

Within this work, aluminum is oxidized via plasma-electrolytic oxidation (PEO) in the presence of organic substances, including reactive monomers. The aim of this approach is to generate polymers and simultaneously bind them to the surface of the freshly generated oxide layers. For this purpose, sheets of aluminum were immersed into electrolytes that comprised either 4 % of sodium acrylate or 10 % of sodium benzoate. The aluminum sheets were oxidized by anodic pulse current at 0.25 A/cm2 for 30–90 s. By this process, predominantly oxidic conversion layers were produced. The presence of the monomers in the electrolyte influenced the passivation and discharge behavior and finally the microstructure of the layers. It further gave rise to organic material in the layer. In particular, infrared attenuated total reflection spectroscopy (ATR-IR) and X-ray photoemission spectroscopy (XPS) show that layers which were generated in the presence of acrylate or benzoate comprised -C-C-, -C=C-, -C-O, and C=O bonds.
Influence of the production route on the phase formation, microstructure and wear behaviour of the high-entropy alloy AlCoCrFeNiTi0.5
Authors: Löbel M , Lindner T , Lampke T
Published: May 2021

Different manufacturing approaches have been investigated regarding their suitability to process high-entropy alloys (HEAs). However, comprehensive investigations on the influence of the production route on the microstructure, phase formation and properties have not been conducted yet. For the current study the alloy AlCoCrFeNiTi0.5 is considered. Previous investigations have proven the formation of phases with predominantly body centred cubic structure for this alloy. Castings are produced by arc-melting. Feedstock material for coating deposition and powder metallurgical processing is produced by inert gas atomisation. For the processing high-velocity-oxygen-fuel (HVOF) thermal spraying and spark plasma sintering (SPS) are applied. Due to the significantly differing process conditions and temperature-time profiles, differences of microstructure, phase formation and resulting properties can be observed. Wear investigations under various conditions have been conducted. Especially under sliding and reciprocating wear conditions the structural defects formed for the thermally sprayed coating cause a reduction of wear resistance. The formation of structural defects could be avoided by SPS. However, the additional tetragonal phase causes a reduction of the wear resistance. The current study contributes to a better understanding of the interaction between process, microstructure and properties.
Shallow neural networks to predict glass transition, crystallization and liquidus temperature of iron-based metallic glasses
Authors: Bobzin K , Wietheger W , Johann L M
Published: May 2021

In the designing of iron-based metallic glasses the prediction of the glass transition temperature Tg, crystallization temperature Tx and liquidus temperature Tl is of special interest. The determination of these temperatures allows not only conclusions about the glass forming ability by calculating glass formation criterions but also about the thermal stability of the alloy in the amorphous state. In the course of alloy development, Tg, Tx and Tl are usually determined by means of differential scanning calorimetry (DSC) on an amorphous sample produced, for instance, by melt spinning or copper casting techniques. The test procedures are time-consuming and cost-intensive. In the present work Tg, Tx and Tl of iron-based metallic glasses are predicted. For that purpose, shallow neural networks with a varying number of neurons are trained using Bayes regularization. The data set for training and testing consists of corresponding literature data. The chemical compositions of iron-based metallic glasses are used as inputs and Tg, Tx and Tl are the outputs. A threshold method is used for data balancing and limiting the number of inputs. Low Root Mean Squared Error (RMSE) and correspondingly high prediction accuracies were achieved during the testing.
High-strength mechanical joints under combined mechanical and medial loads
Authors: Wett D , Radanke M , Lebelt P , Brauns H
Published: May 2021

This paper introduces a test method for joined hot-dip galvanized steelwork test specimens. The specimens joined by means of a lock bolt system were subjected to a simultaneously combined mechanical and medial loading. This was achieved by combining a vibration testing machine and a condensation chamber that was expanded by an electrolyte dosing unit. The electrolyte was dosed on one side of the specimen in the area around the lock bolt head. The zinc dissolution is locally accelerated in the area around the joining element possibly due to superimposed bimetal and crevice corrosion. In addition, the electrolyte enters the space between the joined steel sheets and initiates corrosion processes there, too. Besides the expected zinc ions, potassium ions were also detected in the collected electrolyte by means of elemental analysis. These are originally part of the friction-increasing coating.
The influence of direct powder rolling parameters on the properties of aluminium strip
Authors: Kunene K , Bemont C P , Cornish L A , Dittes A , Grund T , Sinclair P , Lampke T
Published: May 2021

Direct powder rolling (DPR) can be used to create metallic sheet at a reduced cost compared to traditional methods. The process is particularly relevant for metals that are beneficiated to a powder form. The DPR process, however, is not yet optimised and the material properties corresponding to DPR sheet do not compare well with sheet produced from rolled metallic billet. This study explores the effect of DPR input parameters on DPR aluminium sheet material properties. Roll speed, roll gap, sintering time and sintering temperature are shown to have an impact on the density, microstructure, hardness and ductility of DPR aluminium strip. It is shown that a low roll speed and a small roll gap produced the most dense strip. A roll gap of 0.7 mm and roll speed of 0.366 rpm produced green strip with a density of 90% of cast aluminium while a roll gap of 0.8 mm and roll speed of 0.73 rpm produced green strip with a density of 79.6% of cast aluminium. In addition, a Vickers hardness analysis and a three-point bending test show that increasing the sintering temperature of the green DPR strip will produce softer aluminium strips with higher ductility, as expected.
Influence of the aluminum die casting process on PEEK layered CFRP in the manufacturing of a hybrid connection
Authors: Marx A , Schmid A , Haubold T , Pursche L , Schiebel P , Herrmann A
Published: May 2021

Lightweight design is used as a key technology in a variety of fields to achieve significant weight reduction. Due to its low density in combination with high strength, CFRP and aluminum are predestinated lightweight materials. However, the joining of this material combination is still performed using common technologies like adhesive or mechanical joining. A major challenge at the joining of this material combination is the corrosion behavior. Therefore a novel approach of a hybrid connection between CFRP and aluminum was developed by using the HPDC process of aluminum. During efficient HPDC process, a CFRP structure is recast with aluminum (AlSi10MnMg). To resist the shortly appearing temperature of 700 °C from the liquid aluminum melt, the CFRP is coated with a layer of PEEK. This leads to a material transition, which spatial separates CFRP and aluminum and a hybrid connection with tensile shear strengths up to 22 MPa. Within this work, the influence of the several processing steps on the PEEK layer and the structure of the CFRP was investigated. DSC and TGA results show no significant change on thermal properties of the PEEK. Imaging investigations show the appearance of heat induced volatilizations in the PEEK layer of the hybrid specimens after the HPDC process.
Electrochemical testing of thermal spray coatings using gel electrolytes
Authors: Kutschmann P , Lindner T , Grimm M , Lampke T
Published: May 2021

The use of electrochemical methods allows fast and inexpensive corrosion measurements of bulk materials with high significance. In the case of thermal spray coatings, electrolyte penetration into open pores up to the substrate material can cause undesired mixed potentials. Furthermore, the implementation of complex geometries or rough surfaces remains a problem. Preconditioning of the surface or the use of the electrochemical cell is required to eliminate leakage. Therefore, reliably measuring corrosion is still a challenging task. This undermines fast monitoring of corrosion performance as a part of the production process. Gelling agents are investigated to increase the viscosity of many electrolytes. A procedure has been developed to determine the concentration level and the mixing conditions. Passivation and pitting-corrosion testing are performed on thermal spray AISI 316L coatings. The electrochemical potential curves as well as the corroded surface layers were studied in comparison to a liquid electrolyte. The suitability of the test on rough surfaces in the sprayed condition was investigated. The results prove the novel approach as an alternative to established electrochemical test methods with extended application range.
Advanced corrosion resistant cylinder-bore coatings
Authors: Schilder B , Garling A , Mayer U , Grabs R , Lampke T
Published: May 2021

This paper presents a novel approach to enhance the corrosion resistance of cylinder-bore coatings for internal combustion engines by changing surface characteristics and microstructures of the coating and utilizing alternative materials. The approach of this study refers to the knowledge of the complex gas-flow conditions during the internal-diameter coating of cylinder-bores using a twin-wire arc-spray process. Selective influencing of the gas flow enables the preparation of sample coatings with inhomogeneous and more homogeneous microstructures and surfaces. The various coatings were exposed to corrosive environments using the Kesternich testing method and an alternating immersion test. Significant improvements in corrosion resistance have been demonstrated by up to 50 % through altering the microstructure of the coating and almost 100 % by additional changing the spraying material. The study reveals an increased protection of cylinder-bore coatings against corrosive attacks through a homogeneous microstructure prepared in oxygen-poor coating conditions.
Effects of Y content on microstructure, mechanical and damping properties of Mg–Al–Y alloys
Authors: Ma Hongbin , Wang Jinhui
Published: May 2021

The effect of Y on microstructure, mechanical properties, and damping properties of the extruded and annealed Mg–1Al–xY (x = 4, 6, 8) alloys has been studied. The grain sizes of Mg–Al–Y alloys decreased with the increase of Y. The mechanical properties of Mg–Al–Y alloys improved with increasing Y content. The temperature-dependent damping spectrum could be divided into three parts. The vibration frequency weakly affects the damping capacity of Mg alloys. The result of temperature-dependent damping capacity indicated that the overall trends of the tan ϕ decreased at first and then increased with the Y Mg–Al–Y alloys at temperatures between 300 K to 675 K. There were two temperature damping peaks P1 and P2, which was caused by grain boundary relaxation and grain boundary slip, respectively. Grain boundary slip can significantly affect the damping capacity of the Mg alloys at high temperature. The results of XRD showed that the residual stresses existed in the Mg–1Al–xY (x = 4, 6, 8) alloys after the damping test, which was consistent with the results of damping performance test.
Attributing snow cover extent changes over the Northern Hemisphere for the past 65 years
Authors: Guo Hui , Yang Yuting , Zhang Wenjie , Zhang Cicheng , Sun Hui
Published: May 2021

Snow is a crucial component of the cryosphere and its has been experiencing a significant decline for the Northern Hemisphere (NH) (35–90°N) snow cover extent (SCE) in March-April over the 1948–2012 period. However, the causes of this historical snow cover decline are still uncertain. Here, based on the Global Land Data Assimilation System version 2.0 (GLDAS) reanalysis reanalyzed snow cover extent (SCE) and climate model simulations that separate different anthropogenic forcings, we attribute changes of spring SCE over the NH to anthropogenic and natural climate forcings using an optimal fingerprint technique. We find that fingerprints from greenhouse-gases (GHG) and stratospheric aerosols can be clearly detected in the historical SCE records, whereas natural forcing has not contributed to the long-term SCE trend in a discernible way. The GHG-induced warming is primarily responsible for the NH SCE decline, which, however, has been partly offset (by ∼16%) by aerosol-induced climatic cooling. Our findings confirm the negative effect of warming on SCE changes yet highlight the positive role of aerosols in slowing SCE decline over the past 65 years.
The Challenge of Achieving Immunity Through Multiple-Dose Vaccines in Madagascar
Authors: Jones Forrest K , Mensah Keitly , Heraud Jean-Michel , Randriatsarafara Fidiniaina Mamy , Metcalf C Jessica E , Wesolowski Amy
Published: May 2021

Administration of many childhood vaccines requires that multiple doses be delivered within a narrow time window to provide adequate protection and reduce disease transmission. Accurately quantifying vaccination coverage is complicated by limited individual-level data and multiple vaccination mechanisms (routine and supplementary vaccination programs). We analyzed 12,541 vaccination cards from 6 districts across Madagascar for children born in 2015 and 2016. For 3 vaccines—pentavalent diphtheria-tetanus-pertussis-hepatitis B-Haemophilus influenzae type b vaccine (DTP-HB-Hib; 3 doses), 10-valent pneumococcal conjugate vaccine (PCV10; 3 doses), and rotavirus vaccine (2 doses)—we used dates of vaccination and birth to estimate coverage at 1 year of age and timeliness of delivery. Vaccination coverage at age 1 year for the first dose was consistently high, with decreases for subsequent doses (DTP-HB-Hib: 91%, 81%, and 72%; PCV10: 82%, 74%, and 64%; rotavirus: 73% and 63%). Coverage levels between urban districts and their rural counterparts did not differ consistently. For each dose of DTP-HB-Hib, the overall percentage of individuals receiving late doses was 29%, 7%, and 6%, respectively; estimates were similar for other vaccines. Supplementary vaccination weeks, held to help children who had missed routine care to catch up, did not appear to increase the likelihood of being vaccinated. Maintaining population-level immunity with multiple-dose vaccines requires a robust stand-alone routine immunization program.