bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-dimensional transition metal dichalcogenides for lead halide perovskites-based photodetectors: band alignment investigation for the case of CsPbBr3/MoSe2
Authors: Huang Le , Huo Nengjie , Zheng Zhaoqiang , Dong Huafeng , Li Jingbo
Published: May 2020

The distinguished electronic and optical properties of lead halide perovskites (LHPs) make them good candidates for active layer in optoelectronic devices. Integrating LHPs and two-dimensional (2D) transition metal dichalcogenides (TMDs) provides opportunities for achieving increased performance in heterostructured LHPs/TMDs based optoelectronic devices. The electronic structures of LHPs/TMDs heterostructures, such as the band offsets and interfacial interaction, are of fundamental and technological interest. Here CsPbBr3 and MoSe2 are taken as prototypes of LHPs and 2D TMDs to investigate the band alignment and interfacial coupling between them. Our GGA-PBE and HSE06 calculations reveal an intrinsic type-II band alignment between CsPbBr3 and MoSe2. This type-II band alignment suggests that the performance of CsPbBr3-based photodetectors can be improved by incorporating MoSe2 monolayer. Furthermore, the absence of deep defect states at CsPbBr3/MoSe2 interfaces is also beneficial to the better performance of photodetectors based on CsPbBr3/MoSe2 heterostructure. This work not only offers insights into the improved performance of photodetectors based on LHPs/TMDs heterostructures but it also provides guidelines for designing high-efficiency optoelectronic devices based on LHPs/TMDs heterostructures.
Keep it real: selecting realistic sets of urban green space indicators
Authors: Carmen Raïsa , Jacobs Sander , Leone Michael , Palliwoda Julia , Pinto Luís , Misiune Ieva , Priess Jörg A , Pereira Paulo , Wanner Saskia , Ferreira Carla Sofia , Ferreira António
Published: May 2020

With increasing urbanisation, urban green spaces are expected to be crucial for urban resilience and sustainability, through the delivery of ecological, economic and social benefits. In practice, however, planning, management and evaluation of urban green spaces are rarely structured and evidence-based. This represents a missed opportunity to account for, track and foster the multiple benefits that green spaces are expected to deliver. To gain insight into this gap, this study assesses the availability and uptake of relevant evidence by city governments. Interviews, focus groups and quantitative surveys were applied in four medium-sized European cities: Coimbra (Portugal), Genk (Belgium), Leipzig (Germany), and Vilnius (Lithuania), covering the main governance and climatic gradients in Europe. Using straightforward data exploration and regression, we analyse which ecological, economic and social indicators are typically chosen by cities and why. Together with the city stakeholders, we derived a common set of benefit categories and key performance indicators which can be adapted to diverse local contexts. We conclude that cities tend to make pragmatic decisions when composing their indicator sets, but nevertheless cover multiple urban green space dimensions. Finally, we explore how indicator choice could be optimised towards a complementary and credible indicator set, taking into account a realistically feasible monitoring effort undertaken by the cities.
A note on the Drinfeld associator for genus-zero superstring amplitudes in twisted de Rham theory
Authors: Kaderli André
Published: May 2020

The string corrections of tree-level open-string amplitudes can be described by Selberg integrals satisfying a Knizhnik–Zamolodchikov (KZ) equation. This allows for a recursion of the α′-expansion of tree-level string corrections in the number of external states using the Drinfeld associator.

While the feasibility of this recursion is well-known, we provide a mathematical description in terms of twisted de Rham theory and intersection numbers of twisted forms. In particular, this leads to purely combinatorial expressions for the matrix representation of the Lie algebra generators appearing in the KZ equation in terms of directed graphs. This, in turn, admits efficient algorithms for symbolic and numerical computations using adjacency matrices of directed graphs and is a crucial step towards analogous recursions and algorithms at higher genera.
Research on the Signal Characteristics of Internal Gas Leakage in Safety Valve
Authors: Haodong Ma , Rui He , Dianjing Chen , Haodong Ma
Published: May 2020

Based on the acoustic emission theory, this paper explores the signal characteristics of internal gas leakage in safety valve. In this paper, a simulation test-bed and an acoustic emission signal detection system for internal leakage in safety valve are designed and built. Through theoretical analysis and experimental research, the influence of factors such as inlet pressure of safety valve, size of leakage hole of sealing surface are explored, and the quantitative relationship between the gas volume leakage rate and the average signal level ASL of the characteristic parameters of acoustic emission signal is established.
Analysis of Importance of Engineering Survey in Construction Engineering Quality Management
Authors: Liguo Liu , Caixia Zhang
Published: May 2020

Engineering survey is an important technology applied in the quality management of construction engineering. By conducting engineering survey, it can provide necessary data support and measurement methods for the early exploration, mid-term construction, and later acceptance quality management of construction engineering. In the process of construction quality management, how to apply the engineering measurement technology reasonably becomes an urgent problem to be solved. This article will give an overview of engineering survey, and describe the important role of it, and give some opinions and suggestions.
Real-time Monitoring System of Leakage Current for Electric Submersible Pump
Authors: Song Nan , Wang Min , Dang Bo , Liu Shenghu , Ren Zhiping
Published: May 2020

With the increasing exploitation of marine gas, electric submersible pump technology has attracted more and more attention. Under the influence of the bad underground environment, the insulation performance of the electric submersible pump will gradually deteriorate during its operation, resulting in current leakage, causing phase-to-phase open circuit, fire or electric leakage to ground and other dangerous phenomena, which brings destructive damage to the electric submersible pump equipment. In order to solve this problem, this paper designs a real-time monitoring system of the leakage current for the electric submersible pump based on the principle of current mutual inductance and transducing, and constructs the indoor well condition simulation experiment. The experimental data shows that the system can monitor and display the current leakage of the electric submersible pump in real time to ensure the safe operation of the electric submersible pump.
Research on Multi-points Measurement of a Novel Alternate arrangement dynamometer Model
Authors: Danaish  , Zongjin Ren , Jun Zhang , Akbar Muhammad Ayaz
Published: May 2020

The basis of this research is to design and fabricate a new type of alternating arrangement of three-axis piezoelectric sensors dynamometer for measuring six-component force/torque measurement. The system consists of a long dynamometer with eight tri-axial piezoelectric sensors alternatively distributed. The design theory of the piezoelectric six-axis force dynamometer is established, including a finite element model (FEM: ANSYS analysis) and experimental model (static and dynamic calibrations). Structural design is constructed for analyzing the operating principle and performing the experimental measurements. The multipoints measurement (MP-M) model is fabricated based on the established alternate arrangement pattern and force application of multi-points allocation to apply the force/torque. Therefore, this work describes linearity error, repeatability error and cross-talk error of the constructed model. However, the designed model is not limited only to an alternate arrangement pattern of tri-axial sensors. But in the future, other types of arrangements will be researched and will be experimentally performed.
The Positioning Accuracy and Performance Simulation Analysis of BeiDou-3 in Cote d’Ivoire
Authors: Eugene Krou Sub-Lieutenant Brou , Li Houpu , Song Yue
Published: May 2020

BeiDou Navigation Satellite System will operate world widely in 2020. Therefore, it is very important to master the accuracy and positioning performance of BeiDou-3 in West Africa. The number of visible satellite, the navigation accuracy and Geometric Dilution of Precision (GDOP) of BeiDou-3 (3 GEO-3IGSO-24MEO) are simulated using STK software in Cote d’Ivoire. Using data of five stations in Cote d’Ivoire, the simulation results are compared for BeiDou-3 and GPS. Thus, the results are allowed to possess a database about the positioning performance of BeiDou-3 not only for Cote d’Ivoire but also benefit for surrounding Regions of the Gulf of Guinea.
Development and Current Situation of Radar Performance Parameter Measurement Simulation Training Platform
Authors: Wang Jun , Deng Bin , Li Chuanqi
Published: May 2020

The measurement of radar performance parameters is the basic work of radar support forces, and the development of simulation training platform has a very good role in promoting this work. This paper describes the current situation of radar parameter measurement, introduces the development of equipment simulation training platform, and combs the development process of radar performance parameter measurement simulation training platform. At last, the practical requirements of the simulation training platform for radar performance parameter measurement are put forward, that is, by building the simulation training platform for radar main parameter measurement, to meet the requirements of the new two-level maintenance system for the parameter measurement of military maintenance personnel.
Air-Ground Rotary Scanning Imaging System for Ground Vehicles Based on Passive Infrared Detection
Authors: Lei Bingshan , Hao Weina , Zhu Wenbin , Yan Keding
Published: May 2020

General target detection system is based on active detection method, which is usually of poor concealment and bulky. In order to improve the concealment and dexterity of airborne detection, an airborne infrared scanning imaging system for ground vehicles based on passive infrared detection is proposed. Under the condition of guaranteeing the minimum effective detection interval, a rotary scanning dynamic detection model is established based on the principle of single-point passive infrared detection, and the relationships between the detection distance, the rotating angular velocity, the scanning angle, the relative motion velocity and the size of detection area are obtained. According to the expression of infrared characteristic of ground vehicles, the relationship between the response voltage of radiation signal and the relationships among the detection distance is obtained. Based on the projection distribution of the infrared feature area received by the infrared detector, the signal response expression including the size information of the target is obtained at a certain rotating angular velocity. Finally, through simulation and experiment, the system can effectively acquire the signal intensity and signal response width information in the infrared feature area of ground vehicles between the detection distance of 5.4 m and 33.4 m, which verifies the effectiveness of the system.
Numerical simulation of reflected wave characteristics in oil wells measured by Acoustic method
Authors: Wang Ke , Liu Yanping , Wu Jie , Gao Jianshen
Published: May 2020

In order to analyze and identify the corrosion of the inner interface of the coupling, perforating and casing, or the collapse and depression of the casing, as well as the reflection form of the dynamic liquid level, the COMSOL finite element analysis software was used to carry out numerical simulation research on the above situation, and its response characteristics were obtained through calculation. In this paper, three-dimensional propagation characteristics of acoustic waves in the annulus of the oil jacket were studied using signal sources of different polarities. The results showed that when the polarity of the signal source was positive (negative), the coupling reflection signal was first positive (negative) and then negative (positive), and the perforation reflection signal was first negative and then positive (positive then negative). The waveform of the reflection signal in the case of corrosion or casing collapse was consistent with the waveform of the perforation reflection signal; the reflection signal of the moving surface was of the same polarity as the emission signal source. When the signal source was a positive-negative superimposed source, the conclusion obtained by applying the above-mentioned positive (negative) polarized signal source was based on the polarity of the first peak of the superposed source. The research results can provide strong support for the popularization and improvement of related theories, and correct reference standards for the performance verification of echo processing methods, as well as important theoretical basis for the correct identification of echo positions on the Dynamic fluid interface.
Investigation into position deviation effect on micro newton force sensor
Authors: Xu Li , Wang Shuxiang , Zheng Peiliang , Huang Zhenyu , Luo Xudong
Published: May 2020

The position deviation effect on force sensor with a resolution of micro newton scale was investigated by theory model analysis and numerical simulation method. The finite element method and theoretical model were used to analyse the influence of the electrostatic micro force sensors when the electrode position of the cylindrical capacitor changed. Relationship between the sensor output micro force and the position deviation of the internal electrode in the cylindrical capacitance was obtained. It was found that different position deviation form had different degrees of influence on the sensor’s output result and the regions with little effect by position deviation were existed. For translation along Z-axis, the region was [-4 mm, 14 mm]. For translation along r-axis, the region was [-0.2 mm, 0.2 mm]. And for rotation around r-axis, the region was [-1°, 1°]. The corresponding maximum errors of the micro force output were 1.49%, 2.09% and 2.20%, respectively.
Observing the Polarization Dependent Light Shifts Using an Atom Fountain
Authors: Hu Qingqing , Wang Qian , Luo Yukun , Xu Fufang , Jiang Wei , Wei Rong
Published: May 2020

We theoretically predicted and experimentally demonstrated the sinusoidal shifts of the 87Rb atom Raman transition frequencies as the polarization vectors of the Raman lasers rotate. We also presented the vanish of the differential light shifts for the magnetic sensitive Raman transitions at some elliptically polarized configurations while no vanish for the magnetic insensitive Raman transition. These results are helpful for the evaluation and elimination of the light shifts induced systemic errors in the atomic magnetometer, atomic interferometer, atomic clock and quantum computing.
Research on the Main Problems and Countermeasures in the Construction of University Library Informatization
Authors: Wang Weifeng , Meng Luyang , Wu Lei , Hu Jianfei
Published: May 2020

University library informationization plays an important role in developing reading habits and knowledge literacy of teachers and students in universities. However, most college libraries in China still have problems such as not paying enough attention to informatization construction and low informatization construction. This paper adheres to the problem-oriented, and on the basis of analyzing the problems, puts forward countermeasures and suggestions to improve the level of informationization construction of university libraries.
Research on Cow Gesture Recognition Based on Multi-label Chain GBDT and LR Fusion
Authors: Zhao ZhiQiang , Zhu Zheng , Ye ShunAn
Published: May 2020

In this paper, by wearing a nine-axis motion sensor on the neck of a cow, the three-axis acceleration, three-axis angular velocity and three-axis angular motion data of the cow are collected, and the cow’s sports behavior is divided into six postures: standing, resting, walking, and so on, which are used as secondary marks. After the data is balanced and sampled, the six types of gesture labels are divided into three categories as the first level labels, namely, static, small motion and large motion. Gradient Boosting Decison Tree and logistic regression fusion algorithm are used to learn and predict the first-level label, and the prediction result is used as the new feature to learn and predict the second-level label, so as to achieve the purpose of classification of cow gesture recognition. The experimental results show that the average accuracy of the model is 93.6%, and the AUC value is 96.1%. This study can provide an effective basis for dairy cow on estrus and health monitoring.
Design and Implementation of Unmanned Agricultural Machinery
Authors: Jang Ru , Kasimov Farkhod , Zhang Dong , Kaliyeva Kulyash
Published: May 2020

The unmanned agricultural machinery can greatly improve operating efficiency and can cover a large area of farmland operations with very little manpower, which saves agricultural investment costs. In this paper, the hardware and software design of unmanned agricultural machinery are introduced, the unmanned agricultural machine is developed, the autonomous driving experiments in different paths are carried out, and the accuracy of the operation is tested. The results of the experiments show that the unmanned agricultural machinery has high tracking accuracy and can meet the needs of field operations.
Low-illumination image enhancement algorithm based on multi-feature fusion
Authors: Zhang Xuewei , Sun Xiaojuan , Wang Tianfeng
Published: May 2020

In order to improve the effect of image acquisition under the condition of low illumination, a low illumination image enhancement algorithm based on multi-feature fusion is adopted in this paper. In this algorithm, the illumination information is extracted by bilateral filtering, and the illumination parameters are processed by adaptive gamma correction and limited contrast histogram equalization algorithm. The final illumination parameters are obtained by the feature weighted fusion of the processed parameters and the original illumination parameters. The RGB image is obtained by combining the illumination and reflection parameters, and the enhancement of the image is realized. The experimental results show that the algorithm used in this paper can not only improve the brightness of the image, but also enhance the characteristic parameters of the image, remove the noise, and make the color information of the image fuller and richer
Research on alarm control system based on voice lock
Authors: Rui Wu , Zhao Yang , He Zhang
Published: May 2020

In order to realize the intelligent control and remote control of the safe and improve the efficiency of unlocking, a voiceprint unlocking system is proposed. The research uses voiceprint to control the switch of electronic lock. The core technology of voiceprint lock is speech recognition. Speech recognition technology is to convert speech signal to machine language, so that the machine can recognize the voiceprint. Because of the uniqueness of the voiceprint, compared with other unlocking methods, it has the advantages of high precision, high life, high efficiency, etc. Besides, because the voiceprint does not use the mechanical key to unlock, the efficiency of unlocking is greatly improved. The application of voiceprint recognition technology to the voiceprint lock is a high stability unlocking method, which can greatly improve the safety of the safe. Through mobile app and direct voiceprint input, the remote control of the safe is realized. The recognition rate is over 98%, which greatly improves the unlocking efficiency of the safe.
Research on Digital Pulse Compression Technology of Overlapping Data Splicing
Authors: He Panpan
Published: May 2020

Digital pulse compression technology is an effective technology to solve the contradiction between the maximum operating distance and the range resolution of sonar. However, in practical application, when the amount of data to be processed is large and the segmented processing is needed, the data segmentation may be unreasonable, resulting in the weak peak value of the signal after pulse compression, thus affecting the detection results. This paper introduces a method of overlapping data splicing. By improving the correlation between signal and matched filter, the problem of unreasonable data segmentation is effectively solved.
Adaptive power line communication for intelligent separate layer production with single-core cables
Authors: Changzan Liu , Bo Dang , Ling Yang , Linkang Xu , Ruirong Dang
Published: May 2020

Power line communication (PLC) techniques have been proven to be efficient for the intelligent separate layer production (ISLP) system with single-core cables. However, the permanent mode of the ISLP may cause a continuous change of the resistance and capacitance of the single-core cables due to the long-term effect of high temperature, high pressure as well as the vibration of the bad downhole conditions, which will have great influence on the data transmission efficiency. In this paper, we present an adaptive PLC approach for the data transmission of ISLP with single-core cables. Instead of the precise slide rheostat, program-controlled potentiometer is used to achieve an adaptive decoding algorithm for fast initialization of the ISLP transmission. Moreover, a long-term adaptive method is also proposed to adjust the gain and filter coefficients in real time according to the bit error rate of data transmission systems. Finally, experiments were conducted and the results demonstrate the effeciveness of the proposed adaptive PLC data transmission for the improvement of the efficiency and stability of the ISLP system.
The effect factors analysis of the cave formation based on the LWD resistivity imaging method
Authors: Kang Zhengming , Li Fei
Published: May 2020

The cave formation has strong non-homogeneity and the well logging response mechanism of it is very complex, which is of great significance to be studied. Based on the 3D finite element method, the logging response of the Logging While Drilling (LWD) resistivity imaging tool is simulated. The effects of cave diameter, cave extension and resistivity contrast between cave formation and background formation on ratio of measurement signals are investigated using a single cave model. The results show that the existence of the borehole has a great influence on the measurement signal, so it needs to be corrected or the measurement electrode of the tool should be close to the borehole. When the diameter of the cave is larger than a certain value, the relationship between the cave extension and the measurement signal can be quantitatively described. However, the resistivity contrast between the cave formation and the background formation shows a power index relationship under different cave diameter. The simulation results can provide a theoretical basis for the identification and interpretation of LWD resistivity imaging tool.
Circular Economy: Integrated Design of Fish Tank- Flower Nursery
Authors: Li Xuexia , Wang Yu , Bao Tianyong , Xiang Yirui
Published: May 2020

The internet of Everything has come into reality. Smart home has entered our life and changed our life style. Using traditional methods, consumption of time and labour needs to be considered for family breeding and conservation. Based on analysis and research on the application status of household flower nursery and aquarium equipment, an integration fish tank-flower nursery ecosystem was designed. An interaction between aquarium automatic water exchange maintenance and automatic watering system of flowers and plants can be designed via several techniques, where contains single-chip computer technology, open source Arduino technology and multi-sensor fusion technology. Furthermore, the goal of recycling of water can be fulfilled by using the rich water of fish culture to water flowers. Experiments show that the integrated ecosystem can replace the traditional manual maintenance, save resources and bring people a better home experience.
Characterization of asphalt binders blended with nanomaterial and polymer
Authors: Ali S I A , Abubaker A , Alshetwi A B Z
Published: May 2020

Modification of bitumen binders with polymers and nanomaterials has successes in mitigating various major causes of pavement failures. The aluminum oxide nanoparticles (AI2O3) and Acrylate-Styrene-Acrylonhrtilrei polymer (ASA) were poured on the base bitumen binder 60/70 penetration grade with percentages of 3, 5 and 7% by the weight of bitumen binder. The outcome shows that the inclusion of polymer modified binders (ASMBs) and nanoparticles modified binders (ALMBs) matter has a great deal of impact on the rheological behavior of the bitumen binder at intense temperatures. However, the complex shear modulus (G*) improves the mix of the two modifiers. The increment at 75 °C was 63.70% for five percent ASBMs polymer, while for ALMBs, 71.12% for five percent. Although, the modified bitumen binders show high resistivity to rutting in intense temperatures, upon increment to 80% and 59% for five percent concentration of ASMBs as well as ALMBs chronologically. The refinement of bitumen binders gives an increase in the property of the binder which is the creep recovery for approximately about 69.23% and 62.53%. The use of ASMBs and ALMBs as discovered in this study shows that both modifiers above can mitigate the issues of the bitumen binder at intense temperatures, and five percent is regarded as the maximum constituent of the two modifiers.
Analysis of increment of road traffic accidents in Libya: Case study city of Tripoli
Authors: Ali S I A , Elturki F A A , Jibrel S N
Published: May 2020

Traffic and highway engineers working with law enforcement officials are constantly seeking for better methods to ensure safety for motorists and pedestrians. The planning process requires that engineers collect and maintain traffic safety data, identify the hazards location, conduct studies and establish project priorities. Unfortunately, in Libya, the increase in demand for private transportation in recent years, due to poor or lack of public transportation led to some traffic problems, especially in the capital (Tripoli). Also, the growth of private transportation has significant influences on the society regarding road traffic accidents (RTAs). This study investigates the most critical factors affecting RTAs in Tripoli, the capital city of Libya. Four main classifications were chosen to build the questionnaire, namely; human factors, road factors, vehicle factors, and environmental factors. Moreover, the data was collected from 400 respondents in the study area, and the relative importance index (RII) was used to rank the factors. The results show that human factors have the most significant impacts compared with other factors. Moreover, 84% of respondents considered the over speeding as the most affect factor causes of RTAs while 81% considered the disobedience to driving regulations as the second most influential factor in human factors. Besides, 74% of respondents considered poor brakes or brake failure factors has a high impact on the RTAs among the vehicle factors, while 79% classified poor or non-street lighting factors as one of the most effective factors on RTAs in road factors. The environmental factors have slight influences on RTAs.
Modification of Hydraulic Conductivity of Sandy Soil using Seawater and Alkaline Solutions
Authors: Dawoud Osama
Published: May 2020

Altering soil characteristics by precipitation of the calcium carbonate between soil particles is attracting the interest of geotechnical engineers for a wide range of applications. However, current applied approaches still face challenges such as the high cost of materials, difficult handling of precursors, and hazardous by-products. The study described by the current paper investigated the modification of hydraulic conductivity of sandy soil by chemical precipitation of the calcium carbonate using seawater as the source of calcium. The designed experiment involved treatment of bench-scale soil columns by two readily mixed solutions. One of the solutions served as the source of calcium ions and the other contained carbonate ions. The current paper compares behavior of hydraulic reduction considering different resources. The results showed that the crystals formed in small sizes as a result of the instantaneous reaction of calcium precipitation; and thus, crystals transport with the solution as colloids. Accordingly, reductions in hydraulic conductivity were mainly governed by the filtration mechanisms; and the precipitated calcium carbonate was retained close to the injection point. Conducting treatment using seawater as the source for calcium ions induced 65% reduction in hydraulic conductivity at 5.5 g CaCO3/g soil. This reduction is identical to the case when the artificial source was used. Further treatment by the artificial source of calcium reduced the hydraulic conductivity of sandy soil by 97.2%. These outcomes suggest that the chemically induced calcium carbonate precipitation from seawater can be employed by some geo-environmental applications which are conducted in the vicinity of the shore and require reduction of hydraulic conductivity.
Performance of encased single stone column in layered soil
Authors: Farah R E , Nalbantoglu Z
Published: May 2020

Stone columns were found to be effective, economical and widely-used ground improvement technique in soft grounds. It is important to understand the behavior of stone columns when they are installed in layered soils. This paper presents results from a series of small scale laboratory model tests carried out in unit cell tank to investigate the behavior of floating and end bearing stone columns in layered soils with and without encasement, consisting of loose sand overlying a soft soil. Tests were conducted with loading only the stone column area to estimate the limiting axial capacity of stone column. Laboratory tests were carried out on a column of 10 cm diameter surrounded by layered soil. Test results indicated that the bearing capacity of layered soil has been improved in all cases of stone column applications. The non- encased floating stone columns gave better results than non-encased end bearing stone column. The inclusion of geotextile encasement resulted in further improvement of layered soil and the encased floating stone column had superior bearing capacity improvement.
Properties of high-strength concrete containing well graded rubber particles
Authors: Habib A , Yildirim U , Eren O
Published: May 2020

Discarding of old rubber tires is indeed a very serious environmental problem all over the world represented by a high risk for uncontrolled fires and other environmental and health hazards. It was estimated that every year about one billion tires get to the end of their life span. Recently, the construction industry has taken up the challenge to incorporate recycled materials in concrete mixtures by means aggregate replacement. Nowadays, many researches are focused on investigating rubberized concrete as a structural material due to its enhanced properties such as ductility, energy dissipation and damping ratio. Previous studies have suggested the use of fine rubber particles rather than coarse ones when high strength concrete is targeted despite the fact that using coarse ones provide enhanced energy dissipation, damping ratio and vibration behavior. This study is intended to address the effects of utilizing significant amount of well graded fine and coarse rubber aggregates on the properties of high strength concrete. On the basis of the investigations some mechanical, durability and dynamic tests will be conducted on concrete with different rubber replacement percentages. The results of the experimental works have shown that it is possible to develop high strength concrete when well graded fine and coarse rubber particles is used to replace 25% percent of the natural aggregates. Furthermore, the vibration behavior of the concrete mixture was improved considerably when high content of rubber aggregates was added into concrete.
Viscoelastic properties of EVA interlayer used in laminated glass structures
Authors: Hána T , Eliášová M , Vokáč M , Machalická K V.
Published: May 2020

Laminated glass is getting used more extensively in a current architecture due to its transparency, aesthetic impression, and post-breakage behaviour. Examples of such structures are balustrades, stairs, or facade panels. These are usually loaded in bending. Polymeric interlayer embedded between glass plies has no flexural stiffness, but it can itself transfer shear stress. The rate of this transfer depends on the shear stiffness of interlayer which is time and temperature dependent parameter. Producers of interlayers often do not specify this quantity thus engineers rather neglect the shear interaction of glass plies in perpendicularly loaded laminated glass panels. This paper provides the values of shear stiffness modulus of common interlayer EVASAFE® by BridgestoneTM in time and temperature domain. This shear stiffness is expressed through Maxwell model whose parameters are based on the series of Dynamic mechanical thermal analysis (DMTA) performed on single lap small-scale specimens in Klokner institute CTU in Prague. Results show that shear stiffness of this interlayer is able to provide significant shear coupling of glass plies in broad temperature range of short-term perpendicularly loaded laminated glass structures.
Surface water resource and effect of weather parameters in estimating the annual rainfall: A case study in Lebanon
Authors: Kassem Y , Gökçekuş H , Aljamal J
Published: May 2020

The quality and quantity of freshwater resources are continually decreasing in the world. The objective of this paper is to review the literature on the water resource with a focus on the surface water, quality of surface water in terms of physical and chemical properties in different locations in Lebanon. Moreover, one of the most important sources influencing the surface water is rainfall. Forecasting rainfall is one of the most essential issues in the hydrological cycle. It is very challenging because is still not possible to develop an ideal model given the uncertainty and unexpected variation. In the present study, prediction models using artificial neural networks (ANN) and multiple linear regressions (MLR) are developed to estimate the annual rainfall as a function of weather parameters and geographical coordinates. The annual data used in this study are recorded in 1942 locations in Lebanon. The latitude, longitude, and altitude of the location, global solar radiation, average temperature, wind speed, and relative humidity are used as the input variables and annual rainfall is estimated as the output variable. The measured values are compared versus those predicted by the ANN and MLR models by evaluating R-squared and Root mean squared error.
Moringa Oleifera seeds and Chitosan as alternatives to conventional coagulation agents
Authors: Kučera T , Hofmanová L
Published: May 2020

This article discusses the possibilities of using natural polymers in the water treatment process to replace conventional chemical-based reagents. Mainly part of article presented the results of a laboratory-scale research focused on the use of alternative coagulants in water treatment. Attention was particularly paid to natural cation coagulants derived from Moringa oleifera seeds and chitin. These two coagulant agents were used in laboratory research for treating real raw water. Several series of laboratory jar tests were performed to identify the effectiveness of the selected coagulants in removing turbidity from water.
The information exchange in the construction sector in the age of BIM: a multiple case study from Italy
Authors: Leto A D
Published: May 2020

In recent years, due to the request of public clients, Building Information Modelling (BIM) projects are more vastly deployed in construction sector. Furthermore, BIM seems to be the digital methodology with the potential of enhancing the productivity in the construction sector. However, due to the large number of actors involved in a project, the internal information flow of the same actors and the information flow among the stakeholders need to be refined. This article, therefore, by focusing on the Italian contractors’ perspective aims to examine the contractors’ internal information flow and the information exchange with the stakeholders. 13 interviews were conducted with several individuals in 3 Italian construction contractors. The informants were selected from different levels of the enterprises, spanning from the owners to the foremen. Combined with site visits, these interviews provide an insight of the contractors’ internal information flow and an overview of the information exchange among the contractors and their stakeholders.

The article highlights the current criticalities in the information exchange between the contractors and other actors of the projects. Furthermore, the study points out the opportunities of the digitalisation of the internal and external information flow that could improve the information exchange and the productivity in the Italian construction sector.
Effect of fly ash-limestone dust stabilization on volume change and strength of expansive soil
Authors: Naji J , Bilsel H , Balkis A P
Published: May 2020

The expansive soils in semi-arid and arid regions are affected by swelling-shrinking due to climatic effects, causing damage to lightweight structures. Various methods and materials have been employed to improve the engineering properties of these soils. This paper includes the findings of experimental work conducted studying the effectiveness of use of fly ash (FA) and limestone dust (LS) in the enhancement of the engineering properties of expansive soil sampled from Haspolat, Nicosia. Limestone quarry dust is a by-product produced in quarries as a result of the process of crushing and grinding. Laboratory experiments were conducted on the expansive soil with additive proportions of 5% LS, 10% FA, and 5% LS+ 10% FA by dry mass of the soil at curing periods of 1, 14 and 28 days. The 5% limestone dust and 10% fly ash mixed samples have shown significant increment of up to 220% in CBR value, 82% in volumetric shrinkage, and 100% in swell potential. The study has concluded that the introduction of admixtures to expansive soil generally enhanced the geotechnical properties, exhibiting greater durability and stability compared to the untreated soil. Hence limestone dust and fly ash can be regarded as effective expansive soil stabilizers, also providing cheap solutions to the disposal issue.
Some refurbishment particularities: An older building case study
Authors: Oliveira R A F , Lopes J , Abreu M I
Published: May 2020

Portugal has many old buildings with historical and cultural values in advanced degradation. Many of them have an architectural interest, special values and some other characteristics with interest to preserve, which contribute to keeping the building originality and singularity. These building could be retrofitted for new facilities of uses increasing the levels of comfort similar to new buildings. However, all project management of that kind of buildings is more specific, complex and requires special knowledge in the management of the particularities of their work, even other factors related with misunderstandings, inheritance problems, and many others. This research describes a case study that involves the surveying of constraints and other problems concerning the retrofitting works of an old building located in Montesinho village (Bragança-Portugal). In their retrofitting works were applied some parameters of the “Retrofitting management system for buildings located in consolidated urban areas” to support the project design and the building existential particularities. Besides, the management system considers regulations obliged, sustainable practices and possible constraints particularities for that old building case study’s project management. The results show constraints, problems, but also solutions application to solve and reduce them, being a contribution to many other old buildings with similar retrofitting needs.
The effect of stone column area replacement ratio on seismic behaviour of foundation
Authors: Safkan I , Derogar S , Anywar J
Published: May 2020

Tall buildings require additional foundation solutions in order to resist the applied actions on soft soil sites. Nowadays the piled foundations are often altered by stone column solutions, as a cheap alternative. Structures built on soft soil or stiff soil, generally results in different behavior under earthquakes. However, the earthquake behavior of the stone column solution on different types of soil is still unclear. This paper aims to investigate the influence of different characteristics of soil structure interaction on the seismic response of stone column matt foundation. A reinforced concrete matt foundation was simulated with parametric soil stiffness and area replacement ratio of stone column. An analytical method was used to model the soil profile and appropriate ground motion data were incorporated for the analyses. The comparative results were presented and highlighted in terms of soil amplification and seismic response.
Mathematical model of compressor-condenser unit
Authors: Tatarenko I V , Mitropov V V , Nikitin A A
Published: May 2020

The article aims to consider a mathematical model of a compressor-condenser unit, based on the piston compressor with frequency control. The accepted initial data are temperatures and relative humidity of environment and a cooled room, geometrics of the main unit elements. CoolProp library was used for calculation of thermodynamic and thermophysical parameters. The flowchart of calculation of the compressor-condenser unit is provided in the article. The evaluation of the impact of change in environmental relative humidity on the heat transfer coefficient of the condenser has been made.
Investigation of the influence of 3D printing modes with ceramics and sintering on the shrinkage process of thin-walled models
Authors: Piterskov P , Egorov S , Boyko E , Grigoriev M
Published: May 2020

The subject of this study focuses on the effect of 3D printing and heat treatment of thin-walled models made of ceramic paste. The plates with dimensions of 20*5*40 mm were used as the models. The methodology includes the creation of ceramic objects using 3D printing by the SLA method (stereolithography) and their further heat treatment. The surface quality and the shrinkage percentage of samples printed in different modes and thermally processed under different conditions are compared. It was found that with a decrease in layer thickness and particle size, as well as an increase in the duration of heat treatment, the surface quality of the samples improves and the percentage of shrinkage decreases approximately 2 times. Using new modes and improved heat treatment conditions, samples with the least number of cracks and a lower percentage of shrinkage were obtained, which allows using this process to create ceramic products of higher quality. The method of creating ceramic products used in the work in the future can be applied in such industries as aircraft manufacturing, medicine, biotechnology and other fields.
Regulation of powder particle sizes during plasma spraying
Authors: Ermakov B S , Ermakov S B , Pavlenko A , Vologzhanina S A
Published: May 2020

One of the factors constraining the development of 3D technologies is the shortage of powders for additive machines. St. Petersburg Polytechnic University (SPbPU) is developing the design and production of plasma nozzles to produce metal powders and alloys intended for additive machines. The article discusses the results of studies of the effect of pressure powders and flow rate generated in the spray chamber in the production of powders from 08Cr18Ni10Ti and CrNi60BWoTi alloys on the particle size distribution.
Features of the use of light alloys in the marine climate of the arctic zone
Authors: Ermakov S B , Ermakov B S , Andreev A K
Published: May 2020

The movement of mining and processing industries to the North poses the task of analyzing the performance of materials traditionally used in structures and products. The paper presents the results of comparative studies of magnesium alloy MA2-1 and aluminum alloy AMg6 in the marine climate of Northern latitudes. The studies were carried out after simulating the long-term operation and storage of alloys in northern latitudes, namely after long 1000-hour exposures at a temperature of -600 ° C, aging in a salt fog chamber. We analysed the impact of external climatic factors, typical of northern latitudes, on the mechanical properties and a comparative assessment of the corrosion resistance of alloys in a marine climate.
Lanthanide doping of AIIIBV crystals
Authors: Romanov V V , Ermakov B S , Kozhevnikov V A , Stelmakh K F , Vologzhanina S A
Published: May 2020

The state of rare earth impurities at concentrations of about 1018 cm−3 in volume-doped AIIIBV semiconductor crystals can be described in the framework of the model of quasi-molecular rare earth centers of Ln2O3 type and spontaneous polarization regions-coupled spin-polarons localized on small donors.
Specificities of control over multifactorial objects in food production
Authors: Balyubash V A , Alyoshichev S E , Pashkova E A , Ivanov V L
Published: May 2020

The research deals with control methods of multifactorial objects of food production, representing diverse technological processes occurring in continuous, discrete-continuous and discrete modes. This is especially relevant for systems in food production having the series connection of technological units, separated by apparatus-technological capacities and resistances. For such units, a transient delay value is significantly greater than that of single-capacity objects. A solution proposed: the use of two-loop automatic control systems capable of improving system quality parameters in facilities of chemical and technological processes. The two-loop automatic control system is relevant when the object is subjected to frequent disturbing influences from the regulator and has a low inertia parameter. The internal control loop suppresses arising internal disturbance caused by the specifics of the process itself, and the external loop is responsive to disturbing influences coming from outside, e.g., with changing properties of the incoming raw materials.