bluuebunny/crossref_metadata_2025 huggingface dataset:
Combination of Biological and Hydrothermal Pretreatment of Mixed Rice Biomass for Fermentable Sugars Production
Authors: Kian Thing Ang , Shamsudin Saleha
Published: July 2020

Rice biomass is one of the most staple agricultural by-products in Malaysia. In this study, mixed rice biomass (MRB) which combines rice husk and straw in certain ratio was used to produce the fermentable sugars. White-rot fungal strain, P.chrysosporium was used in biological pretreatment for 7 days (30°C). The pretreatment was proceeded by hydrothermal autohydrolysis for further removal of hemicellulose. The reducing sugar of soluble solid mixed rice biomass after autohydrolysis process was determined (0.225g sugar/g MRB). The characteristic of raw and insoluble solid pretreated MRB was observed by Scanning Electron Microscopy (SEM) and the functional groups changes were determined by Fourier Transformed Infrared (FTIR). The parameters of enzymatic saccharification were optimized using Central Composite Design for Response Surface Methodology by setting the concentration of commercial cellulase enzyme used, Celluclast 1.5L from 5 FPU/g to 15 FPU/g and incubation times from 24 to 72 hours. It was discovered that fermentable sugars production was increased from 0.098g sugar/g MRB (0.125 g/L) to 0.248g sugar/g MRB (0.319g/L) at optimized condition 82 hours incubation time and 10 FPU/g enzyme concentrations. Hence, the total reducing sugar produced was calculated as 0.473g sugar/g MRB and saccharification was determined as 66.31%.
Effect of Cycling Time Strategy on The Treatment of Industrial Latex Wastewater with Granular Sludge
Authors: Rashid N A , Abdul Rani A L , Omar M F , Abdullah M A H
Published: July 2020

Effects of cycling time on the performance of granular sludge in sequencing batch reactors (SBR) were evaluated. Two reactors, reactor 1 (R1) and reactor 2 (R2) was introduced to industrial wastewater with varying chemical oxygen demand (COD) loadings from as low as 0.01 to 0.28 kgCOD/m3/d. However granules in R1 utilizes cycling time of 24 hours whilst R2 utilizes cycling time of 4 hours. The overall performance for both reactors were excellent, where COD removal efficiency was kept at about 78 % to 98 % removal. Although higher COD removal was observed for both reactors, granulation did not occur in R1 when applying cycling time of 24 hours. In contrast to R2, decrement of cycling time to 4 hours promotes the growth of dense and structured sludge granules.
Microwave Dielectric Analysis on Porous Hydroxyapatite/Starch Composites with Various Ratio of Hydroxyapatite to Starch
Authors: Chong You Beh , Ee Meng Cheng , Abu Bakar Shahriman , Fazli Mohd Nasir Nashrul , Swee Kheng Eng , Shukry Abdul Majid Mohd , Ridzuan Mohd Jamir Mohd , Shing Fhan Khor
Published: July 2020

This study aims to investigate the dielectric response of the porous hydroxyapatite/starch composites by varying the starch proportion in determining the feasibility of the microwave sample characterization technique in bone tissue engineering. The porous hydroxyapatite/starch composites were fabricated by using natural starch (gelatinization and retrogradation) through the solvent casting and particulate leaching technique. The dielectric constant (ε′) and loss factor (ε′′) of the complex permittivity of the porous hydroxyapatite/starch composites were measured in the Ku band frequency of 12.4-18.0 GHz. ε′ and ε′′ of the porous composites increase with frequency. The highly porous composite that due to higher starch proportion exhibit higher ε′ and ε′′, resulting in the significant dielectric responses.
Crack Detection on Sheared-Edge of Ultra-High Strength Steel Sheet by Using Acid Immersion
Authors: Azzmer S. , Jaafar H. , Tajul L. , Sulaiman M. H. , Zailani Z. A.
Published: July 2020

In trimming of ultra-high strength steel (UHSS) sheet, the high strength of the sheet usually results in large fracture and low burnish surfaces on the sheared-edge. For metal stamping industries, large fracture surfaces are unwanted, as it not only deteriorates sheared-edge quality but also leads to delayed-crack. In this study, crack detection by using acid immersion on the sheared-edge of ultra-high strength steel sheet caused by the trimming process was investigated. The ultra-high strength steel sheet of JSC780YN, JSC980YN, and JSC1180YN having different strengths were trimmed and immersed in 35% hydrochloric acid under a controlled time interval. The steel sheet with higher strength was found to produce larger fracture surface after trimming, i.e. more than 50% of the entire sheared-edge is fracture surface. Besides, the larger fracture surface of the steel sheet results in higher crack exposure and higher crack propagation, which in the long run, it can cause failure to the part manufactured using UHSS.
Influence of TiO2 nanoparticles (wt%) onto the physical and mechanical properties of the TiO2-geopolymer paste
Authors: Mahmed Norsuria , Nor Saffirah Zailan Siti , Mustafa Al-Bakri Abdullah Mohd
Published: July 2020

The TiO2-geopolymer paste had been prepared by dry-mixing of the fly ash with various concentration (wt%) of TiO2 nanoparticles (2.5%, 5.0%, 10.0% and 15.0%). Those powder mixtures were then mixed with the alkali activator with the ratio of 2.5 and were cured at room temperature for 28 and 640 days. The phase and chemical bonding analysis revealed that the incorporation of TiO2 nanoparticles did not create any additional phase or functional group, but only physical interaction might have occurred in between the TiO2 and geopolymer matrix. However, the physical properties were depending on the TiO2 nanoparticles content where setting time of the geopolymer can be shortened by the addition of certain amount of TiO2 nanoparticles (up to 5.0 wt%). The water absorption also increased as a function of TiO2 content, due to the formation of the micro cracks as a result from the agglomeration of TiO2 nanoparticles. The compressive strength reaches its maximum value, 85.9 MPa with 5.0 wt% of TiO2 nanoparticles. Beyond 5wt%, the strength decreased almost half of the maximum value, where agglomeration becomes a main factor. While for 640 days of ageing, sample with 15.0 wt% shows triple increment from 30.6 MPa to 95.3 MPa.
Simple and Green Approach Strategy to Synthesis Graphene Using Rice Straw Ash
Authors: Uda M.N.A. , Gopinath Subash C.B. , Hashim U. , Afnan Uda M.N. , Ibrahim Nur hulwani , Parmin N.A. , Halim N.H. , Anbu Periasamy
Published: July 2020

Abundant resources of rice straw and carbon-neutral have a lot of potentials to be converted into various value-added product and become more green due to less utilization of chemical usage. Graphene is one of value-added had been converted from rice straw and was successfully synthesized by using activating rice straw ash (RSA) using potassium hydroxide (KOH) at 700 oC with 1:2.5 impregnation ratio. scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), EDX Analysis with a field emission transmission electron Microscope (FETEM) and atomic force microscopy (AFM). The current results can be the model for comparing the synthesize graphene from other plant sources.
Numerical Study of Magnetohydrodynamic Blood Flow through an Artery with Multiple Stenosis
Authors: Majekodunmi Joshua T , Anwar K. , Abdullah N
Published: July 2020

The study theoretically accounts for the impact of Magnetohydrodynamics on streaming blood through an artery having multiple stenosis regions using the non-Newtonian Cross-rheological model. It is regarded that the streaming blood is unsteady and pulsative. The use of appropriate conditions is predicated on the assumption that the flow is laminar and axisymmetric which makes the problem two-dimensional. The geometry of stenosis was immobilized into a rectangular grid using the radial coordinate transformation. The finite difference scheme was employed for the numerical simulations. Specifically, magnetic field (Hartmann number), Reynolds number and severity of stenosis were varied over the entire arterial length. The results obtained predicted that increase in the Hartmann number and stenosis severity reduces the magnitude of the flow velocity, flow rate but the reverse is the case when the Reynolds number is increased. However, the wall shear stress and the resistance to flow are aided by increasing the Hartman number and the stenosis severity but reduces with increase in the Reynolds number. Hence, it is germane to apply the appropriate magnetic field in treatments otherwise, such patient may be vulnerable.
A Review on Raw Materials and Curing Methods Applied in Production of Ultra High Performance Concrete
Authors: Mohd Zahid M Z A , Abu Bakar B H , Mohamed Nazri F , Ab Rahim M A
Published: July 2020

Ultra high performance concrete (UHPC) refers to cement based materials exhibiting high compressive strength, tensile strength and excellent durability. This paper reviews the raw materials and curing methods currently applied in UHPC manufacturing process. Raw materials, preparation techniques and curing methods have significant influence on properties of UHPC. The use of very high cement content, high strength cement and silica fume may improve the strength and compactness but increase the production cost. The use of high temperature curing leads to denser microstructure and better performance than room temperature curing and water curing do, but obviously limits its application of UHPC. Thus, preparation of UHPC using widely and locally available raw materials such as ordinary Portland cement CEM Type 1 42.5N and common technology such as room temperature curing are trends in production of UHPC.
The Effect of Harvesting Time on the Antioxidant and Antidiabetic Activity of Piper Crocatum (Sirih Merah) Extract
Authors: Rokiah Syd Kamaruzaman Syarifah , Farihan Kasim Khairul , Nor Jaafar Mahmad
Published: July 2020

Piper crocatumis traditionally used as a treatment against diabetes mellitus, minor wounds and inflammation. This study aimed to evaluate the effect of harvesting time on the antioxidant and antidiabetic activity ofP. crocatumharvested at 2, 4, 6 and 8 months and identification of the compounds responsible for antidiabetic activity. The antioxidant activity of the extracts is evaluated by DPPH scavenging activity, total phenolic content (TPC) and total flavonoid content (TFC) tests while the antidiabetic activity is evaluated by alpha amylase and alpha glucosidase inhibition assays. The results show that extracts obtained from harvesting time at 8 months have the highest antioxidant activity with the DPPH scavenging activity, TPC and TFC being 74.90 ± 0.27%, 492.92 ± 1.40 mg GAE/g and 79.58 ± 1.17 mg QE/g respectively and the highest antidiabetic activity with the alpha amylase and alpha glucosidase inhibition activity being 87.05±0.64% and 88.70±0.42% respectively. Principal component analysis (PCA) was also carried out and it is found that principle component 1 and 2 are associated with the harvesting time (81.7%) and extract concentration (12.4%) respectively. Five compounds are identified to be responsible for antidiabetic activity: caffeic acid, p-coumaric acid, cyanidin-3-O-glucoside, tannin and gallic acid.
Portable Water Cooler with Water Heater Using Thermoelectric and Arduino Uno And Powered Using Power Bank
Authors: Fadzly M K , Aqilah S N , Farizuan  , Amarul T. , Irfan A R
Published: July 2020

The purpose of this study is to use water cooler and water heater to improve the convenience of the user so that they can use the water cooler and mobile water heater properly and comfortably. This study focuses on how refrigeration and water heaters use thermoelectric pads as a cooling and heating medium. Peltier works when the voltage is flowing from the power bank. The temperature difference on the surface of the processor allows the heat to occur at a fast rate. Arduino uno is used as a voltage regulator and temperature sensor to improve product performance. concept designs are designed, created and evaluated. The final prototype will include some markers that will be used as temperature readings by cooling and heating. Based on the results shown, the prototype can achieve the desired result with optimized energy consumption. When the temperature supplier produces a good temperature, the amount of water temperature will rise and the heat in the water will reach thermal equilibrium until the cold and hot temperatures reach a better minimum. Therefore, the temperatures in the cold and hot areas are more efficient in achieving thermal equilibrium in rising water.
Stream technologies of data analysis in organizational and technological design in construction
Authors: Kagan Pavel
Published: July 2020

The issues of intellectual processing of large data arrays in construction are considered. The concept of an automated system for analyzing big data is proposed. The technology of data mining assumes the possibility of estimating the time and cost of performing work on the basis of the used organizational and technological models and real indicators of time and labor observed by these models, and, accordingly, the formation of specific technical and economic indicators. Such indicators are of great importance in the current conditions of activity of construction organizations, they are used by the management of construction organizations in the preparation of tender documents, the development of construction organization projects, and in settlements with subcontractors. The proposed sequence of actions when using data mining technology to estimate the time and cost of work and resource consumption will allow at the stage of a feasibility study or decision to conclude contractual obligations to provide a better understanding of future costs and timing of work. This technique assumes the possibility of its use by both data analysis specialists, data scientist and process engineers, BIM managers, and the like and has a number of advantages due to the use of discriminant functions for data analysis.
Problem of damping oscillations of a mechanical system with integral memory
Authors: Bobyleva Tatiana , Shamaev Alexey
Published: July 2020

The paper considers a mechanical system defined by a linear system of integro-differential equations with nonlocal convolution type terms. The problem of controllability is studied for various types of control (boundary and volume-distributed control) and various types of kernels. These kernels simulate the aftereffect of the system. It is proved that in some cases there is no possibility of damping the oscillations of the system for arbitrary initial conditions. In this work, those cases are distinguished when there is the possibility of damping oscillations over a finite period of time for any initial conditions.
Tiered public spaces – a new step in the development of megacities
Authors: Makarov Aleksander , Kalashnikova Yulia , Kalinovsky Sergey
Published: July 2020

The paper analyzes aspects of the formation and development of the concept of public spaces. The classification of public spaces and their requirements are considered. The concept of a pedestrian bridge in the floodplain of the Tsaritsa river is proposed on the basis of generalization and analysis, applying the practice of developing level public spaces to the city of Volgograd, which is characterized by a complex terrain. The bridge will play an important role here. Its main function is communicative, since it could be used for the transition between the Central and Voroshilovsky districts of the city and, especially, for facilitating walks in the Park zone of the floodplain of the Tsaritsa river, since at the moment this zone is divided by the structures of the Volga children’s railway and therefore cannot be fully accessible and permeable space. A recreational function can also be implemented – the bridge will allow you to get into the garden, which can also be arranged on the roof of the Museum “Russia-my history” without climbing stairs, you can also place viewing platforms and a recreation area on the widths of the bridge. The bridge structure itself should become the dominant space that attracts visitors to the “Razdol’e” park.
Reinventing cities towards being smarter
Authors: Sedova Anastasiia , Balakina Alevtina
Published: July 2020

A smart city concept is becoming more popular. Many cities shift directions for the development of to “smart” destination, which is able to address rapid growth in the urban population and climate change. The concept of smart development consists of four dimensions that encompass various elements of smart cities, one of them, the environ-urban dimension, is stressed in this paper. The elements of this dimension are studied as exemplified by nine architectural projects, which won in the Reinventing Cities competition, launched in many cities across the globe. The competition is a call for urban projects to drive resilient and sustainable urban regeneration, which contributes to the idea of smart development. Urban solutions designed for the competition are listed by the authors in order to analyze what are the newest trends to “fill” the environ-urban dimension of smart development. The paper gives recommendations of what principles of urban design should follow architects in order to create projects which can contribute to smarter urban development.
Investigating urban household water - energy nexus towards supporting sustainable and smart city policies: The case of Hanoi City, Vietnam
Authors: Luong N D , Ha U T T , Hung P T , Minh N B
Published: July 2020

Sustainable and smart management of urban water and energy sectors is one of challenges facing by Vietnamese cities today. This study examined the water-energy nexus in urban households by analysing the “cause-and-effect” relationships among four major individual attributes (age, gender, education level, and family size) and three household behaviours (showering, cooking, and washing) with water and water related energy uses for the case of Hanoi City. The amount and component of water and water related energy uses with respect to those household behaviours and individual attributes were explored. The results showed that both water use and water related energy use had relationship with gender, education level, and family size. Specifically, people with more water and energy uses were female with age ≤ 30 years old, especially who have higher education level and live alone. The better understanding on how household behaviours and individual attributes influencing the household water and water related energy uses provided by this study could help the urban planners, policy makers, and relevant stakeholders to identify the opportunities for designing better and smart solutions for household water and energy management, towards achieving the goals of sustainable and smart cities.
Experimental Evaluation of Nano Silica Effects to High Performance Concrete Strength in Early Age
Authors: Ngo Van-Thuc , Bui Tien-Thanh , Lam Thanh-Quang-Khai , Nguyen Thi-Thu-Nga , Nguyen Van-Hau
Published: July 2020

Nano silicate SiO2 (NS) in the high-performance concrete (HPC) mixture is becoming great interest because it improves the mechanical properties of concrete. As the ultra-fine SiO2 particles with a very high ratio of surface area to mass, NS can tightening the structure and produces better quality gel products and thus concrete strength increases. However, the optimal rate of NS in high-performance concrete has not been investigated. This study experimentally evaluates the influence of NS on compressive strength and flexure strength of HPC of which nominal strength is 70MPa. Seven mixtures of HPC at NS rate of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% over the total weight of the adhesive were conducted. Each mixture provides six samples for compressive tests and six samples for flexure tests. Total samples are 336 samples for four ages of concrete. Reliability of test results was carried out and results shown that at the early stage of HPC, an NS ratio of 1.5% shows the optimal value to improve the performance of concrete. This result also helps to apply NS in HPC in quality control in site application.
Effect of multi-adhesives on the properties of the concrete using sea sand and sea water
Authors: Viet Cuong Nguyen , Thi Thuy Van Tran
Published: July 2020

The study about the use of sea sand and sea water as a raw material in concrete production has great significance in terms of ensuring construction time and reducing costs in the exploitation and transportation stages, especially for those with coastal areas and islands. The paper presents the research results of the influences of some adhesive types on the properties of reinforced concrete using local materials such as sea sand and sea-water. From research results, it is initially showed that the effectiveness of using some types of adhesives, increasing corrosion resistance as well as quality of concrete using sea sand and sea-water.
The Properties of High-strength Concrete with High Volume of Natural Pozzolan
Authors: Van Lam Tang , Xuan Hung Ngo , Bulgakov Boris , Aleksandrova Olga , Larsen Oksana
Published: July 2020

This paper presents the properties of high-strength concrete containing a high volume of N-class natural pozzolan sourced from the Northern part of Vietnam. Based on the conducted studies’ results showed that the mechanical properties of the natural pozzolan concrete were generally lower than those of control concrete. However, with effects combined of natural pozzolan and SR-5000F superplasticizer on the microstructure of concrete, mechanical properties of high-strength concrete increases with the amount of natural pozzolan from 10 to 20% by mass of cement, then descends. In addition, the maximum temperature of both conventional and High-strength concrete specimens significantly decreases with the increasing content of natural pozzolan. Furthermore, the relationship between compressive and flexural strength, modulus of elasticity and compressive strength of heavyweight concrete specimens are also determined in this investigation.
Effects of air entraining admixture on the properties of lightweight aggregate concrete
Authors: Duy Nguyen Hieu , Thanh Mai Pham , Xuan Truong T. K. , Viet Anh Phan , Trang Trinh T.
Published: July 2020

In Lightweight Aggregate Concrete manufacturing, there is a stratification of lightweight aggregate during construction process, because bulk density of lightweight aggregates is much smaller than that of cement mortar. This paper presents some research results about the effect of air entrainment additive on the properties of lightweight aggregate concrete. When adding air entrainment admixture into lightweight concrete components with the amount of 0.02 – 0.08% by mass of binder, the stratification and bulk density of fresh concrete reduce, and strength of hardened concrete is also significantly reduced. Therefore, this result indicates that we should only use the air entrainment additive in small amounts (less than 0.02% by mass).
Theoretical foundations of the structure formation of cement stone and concrete
Authors: Khasanov Bakhridin , Irmuhamedova Lyudmila , Firlina G , Mirzaev Temur
Published: July 2020

The analysis of resource-saving technologies led to the main conclusion that up to now high-intensity methods for physical modification and hyper-consolidation of concrete mix and concrete have not been developed. Taking into account the physicochemical principles of the structure formation of cement stone and concrete, the production of particularly high-strength concrete (Kb q> 100 MPa) is possible by using methods of modifying the concrete mixture, hyper-consolidation of the molded concrete taking into account the development of the optimal structure of the material, capable of significant stretch perception. The implementation of this idea in industrial production, apparently, is possible using simple technological methods for preparing concrete mixture, forming axisymmetric products, methods of hyper-consolidation of molded concrete and physical modification of concrete mixture, for example, by squeezing excess mixing water and entrained air [1].
Ultrasonic modifications of fine-grained limestone concrete
Authors: Belov Vladimir , Kuliaev Pavel , Barkaya Temur
Published: July 2020

The structure formation of cement stone of fine-grained limestone concrete during hydration hardening of cements and filler based on them occurs due to the development of polydisperse and polymineral conglomerate, a process associated with an increase in the volume of crystallohydrates in relation to the volume of the original cement minerals, mixed with water. Structure formation is accompanied by the process of compaction of the developing system and polycrystallization with the formation of floccules of a porous hydrating mass. In the paper, ultrasonic processing is viewed to accelerate the all- side process of modification of concrete structure and hardening thereby stipulating the growth of strength and durability of concrete.
Development of high-strength self-compacting concrete with low fineness modulus sand
Authors: Smirnov Aleksandr , Dobshits Lev , Anisimov Sergey
Published: July 2020

Self-compacting concrete is a highly flowing concrete that compact under self-weight without any vibration effort. The high workability of concrete mixtures is achieved by the reduction in coarse aggregate content while increasing fines aggregate volume. Usually, coarse quartz sands with fineness modulus more than 2.5 are used as fine aggregate. The use of low fineness modulus sands, characterized by high intergranular porosity and high specific surface area, as a fine aggregate, leads to an increase in the concrete mixture water demand and a decrease in its flowability. In such conditions, to obtain high-workability and high-strength concrete, increased cement consumption is required. The purpose of this study was to develop high-strength self-compacting concrete with reduced cement consumption and using low fineness modulus sand. To achieve this purpose, we optimized aggregates consumption in concrete composition, which achieves minimum aggregate mixture intergranular porosity, best concrete mixture workability without segregation, and maximum concrete strength. It has been established that silica fume and superplasticizer using allows obtaining high-strength self-compacting concrete of strength class B60 with low-quality fine sand and reduced cement consumption of 360 kg/m3. With increasing mixtures retention time before concrete placing, there was an insignificant increase in the flowability of obtained self-compacting concrete mixture and an improvement in the physical and mechanical properties of concrete. Remixing of concrete mixtures and concrete placing after 90 minutes from concrete mix preparation moment allowed to increase concrete strength to 17%, increase its density to 15 kg/m3, and reduce porosity to 25%.
Sustainable management and technologies for recycled construction demolition waste in Vietnam
Authors: Giang N H , Tan N H , Quang N T , Hien N X , Kawamoto K
Published: July 2020

This study introduces the series of activities and results that are contributing for the CDW recycling industry in Vietnam especially for the implementation of the recently introduced Circular No.08/2017/TT-BXD. The equation for estimation of the amount of CDW generated from building demolition was introduced. New management regulations which are guideline for demolition, sorting, transportation and treatment and new Vietnamese standard for specification of testing and acceptance for CDW recycling materials are highlighted. The properties of recycling concrete from a pilot project were tested. The research designed a circle of recycling business that results from research are contributing for the sustainable management and technologies in Vietnam. These activities and contributions will significantly support for the implementation of Government’s new regulation, reducing the solid waste to meet the National strategies for environment as well as open for a new important recycling industry in Vietnam.
Effect of Carbon Nanotube on properties of lightweight concrete using recycled Expanded Polystyrene (EPS)
Authors: Cong Thang Nguyen , Ngoc Duc Han
Published: July 2020

Expanded Polystyrene based Lightweight concrete (EPS-C) is a lightweight material with low compressive strength and high energy absorption capacity. This type of concrete is mainly applied for heat and sound insulation, towards energy saving and sustainable development. In terms of composition, EPS-C is made from a mixture of cement, mineral additives, water, chemical additives, and Expanded Polystyrene Beads (EPS) which are small hollow spherical, impermeable, and non-toxic balls. In this paper, the EPS particles were replaced with recycled polystyrene particles as aggregates for lightweight concrete. Besides, carbon nanotube (nCNT) was added to improve the properties of the concrete. The experimental results show that (i) it is possible to use recycled EPS aggregate in making lightweight concrete with a density of less than 1200 kg/m3; (ii) the combination of nCNT improved significantly the properties of lightweight concrete, i.e. reducing the water absorption, increasing compressive strength; (iii) lightweight concrete with a very low thermal conductivity, corresponding to 0.152 W/m.°C for a sample with a density of 600 kg/m3.
Fine-grained concrete modified with a multifunctional additive
Authors: Pyataev Eugene , Semenov Vyacheslav , Bilonda Tregubova Elen , Kirushok Denis
Published: July 2020

The article presents the results of comparative tests of samples of fine-grained vibropressed concrete for paving blocks with modifiers for volumetric hydrophobization based on a dispersion of calcium stearate, an emulsion of polysiloxane and an additive based on a mixture of a dispersion of calcium stearate and an emulsion of polysiloxane. To increase the operational reliability and durability of the vibropressed paving slab an important role is played by properties such as water absorption, frost resistance and corrosion resistance. The aim of the work is to research of the effectiveness of complex modifying additives to increase the frost resistance and corrosion resistance of fine-grained concrete for paving slabs. The researches were carried out according to standard methods in accordance with current regulatory documents. It was revealed that the additive based on a mixture of a dispersion of calcium stearate and polysiloxane had the greatest hydrophobic effect. Concrete products based on these modifiers have shown significant improvement in properties such as water absorption, frost resistance and corrosion resistance compared to an unadulterated sample and samples based on calcium stearate.
Geoinformation systems at the selection of engineering infrastructure of pumped storage hydropower for the tuyamuyun complex
Authors: Dzhuraev Kurbon , Nasrulin Aydar , Shadibekova Fotima , Kurbonov Shokhboz
Published: July 2020

In this article, we also consider the results of studying the problems and prospects of using information technologies to ensure the introduction of new innovative approaches to analyze engineering infrastructure of future pumped storage hydropower. This study aims to develop a series of advanced Geographic Information System algorithms to locate prospective sites for pumped storage hydropower. It is possible and useful to use the association of outputs from various scientific researches in one GIS-database as a universal tool for modelling. This demonstrates the site searching algorithms can work efficiently in the identification of off-river pumped hydro sites, allowing high-resolution assessments of pumped hydro energy storage to be quickly conducted on a broad scale. As an example of such an approach can be considered as one interconnected system which combination results of work:

- The examples of the methodology for creating digital maps for information support, for the study of the technical parameters of hydropower and irrigation facilities at the level of Tuyamuyun hydroelectric complex.

- System of digital maps and schemes that can be used in the development of environmentally acceptable modes of operation of in engineering infrastructure of hydraulic accumulating power plants.

- The results of monitoring engineering infrastructure using geographic information systems, digital maps are shown, which allow for the design, repair and repair of hydraulic structures to take into account terrain, hydrography and other factors. Except this in work are offered several objects water systems, in which will possible introduce pumped storage power and are motivated to their technical-economic parameters.
Agent-based simulation for gas and dust emissions assessment during construction: A case study in Vietnam
Authors: Toan Nguyen Danh , Sharmak Walter
Published: July 2020

Construction activities account for a significant amount of greenhouse gases (GHG) and fine particulate matter (PM10) emissions, particularly in developing countries with expeditious urbanization. To achieve sustainability in the construction phase, researchers have made considerable efforts to estimate the emissions accurately. Although several building-level emission databases and related calculation systems have been set up in developed countries, there unluckily remains a vacancy in Vietnam. This study aims to integrate Agent-based simulation (ABS) and process-based life cycle assessment (pLCA) based on construction norms and environmental data available in Vietnam to evaluate the GHG and PM10 emissions under the uncertain and dynamic conditions of on-site construction and supply chains. This method is developed and applied in the case study of a 20-storey building in Hanoi. The results indicate that, among all of the construction equipment, the off-site and on-site transport equipment are the dominant cause for GHG and PM10 emissions. The formwork related-material contributed the most to GHG among the auxiliary materials.
Distribution of the forms of reserves of humus in typical seroms formed in geomorphological areas Tashkent-Keles
Authors: Akhatov Abdusamad , Gafurov Baxtiyor , Jakhonov Azizjon , Khalimbetov Azat
Published: July 2020

The article presents the effect of humic substances on the physical, water-physical, and chemical properties of the soil, as well as the release of various forms of humus reserves (total, potential, near, direct). Each form of reserves of humus formed organic substances and their different differences in the composition of humus the soils of the serozom belt of healed, newly irrigated, and old irrigated soils, accumulation of humus content and distribution in the layers of the section profile, changes in the forms of humus reserves in the genetic horizons of the soil. In a typical irrigated sierozem, the content of potential reserves of humus and in the same row the proximal, direct forms of reserve increases. In the soil profile at a depth of 0-120 cm, the potential reserve of humus ranges from 42,88 % to 29,60 %, the closest one is from 49,32 % to 57,20 %, the immediate reserve from 7,80 % to 13,00 %. These figures show that over the years, the use of soil for irrigated agriculture, the degree of their cultivation and the amount of watering aggregates increased.
Prediction of rejection properties and performance of nanofiltration membranes based on scaling prognosis in drinking water treatment
Authors: Efremov Roman
Published: July 2020

Reverse osmosis (RO) and nanofiltration (NF) are widespread for drinking water production from underground water sources; these techniques are used to reduce hardness, iron, fluoride, ammonium, strontium, nitrate, pesticides etc. At the same time, with high efficiency of removing iron, hardness, fluoride, ammonium from source water, nanofiltration membranes are much less exposed to the risk of calcium carbonate precipitation than the traditionally used low-pressure RO membranes. Usually it is important to predict the rejection properties of membranes not only at the launch time of RO/NF unit, but during all operation period and gradual membrane fouling/scaling. The article presents experimental data on determining membrane selectivity (nanofiltration membrane OPMN-K, Russia) for iron. fluoride and ammonium depending on the TDS, water hardness and the amount of calcium carbonate precipitate in the membrane module. Operational guidance has been developed that allow to determine the costs of chemicals for the operation of NF installations depending on the source water quality and membrane type. The above calculations show that the use of nanofiltration membranes instead of reverse osmosis can significantly reduce the cost of operating groundwater treatment facilities.
Mathematical modelling of operation modes of water intake structures’ cooling reservoirs
Authors: Solovyev Alexander , Solovyev Dmitriy , Shilova Liubov
Published: July 2020

The article provides an overview of the tasks of studying heat and mass transfer in reservoirs with hydraulic flows of circulating water from turbine condensers. The conditions of effective reduction of the temperature of the water from the reservoir via a slotted water intake working on the principle of a hydraulic siphon are considered. The scheme of the slotted siphon-type water intake is presented, as well as its technical implementation. The system of differential equations for the numerical calculation of the parameters of cooling circulating water in reservoirs with siphon culverts is designed. An assessment of the effectiveness of the use of hydraulic slit water intakes in the cooling systems of the recycled water of thermal power plants is contained in the conclusion.
Flow of waste and a method for prediction of demolition waste generation from buildings – A case study in Hanoi, Vietnam
Authors: Nghiem H T , Tran V C , Hoa P D , Kieu T S , Giang N H
Published: July 2020

Being the capital of Vietnam, a dynamic developing country, Hanoi is experiencing a rapid rate of urbanization and economic growth which leads to the continuing increase of construction and demolition activities. In the recent few decades, construction and demolition waste has been accounted for a large amount of solid waste in urban areas, among which demolition waste (DW) is the major content. This study aims to sketch the flow of DW post-demolition, as well as to provide an approach to predict the estimated DW generation in the future in Hanoi. Data of DW generation rate from previous study in Hanoi is combined with statistics of construction in the city to work out a reasonable model of projection of DW for further recommendations for managing this type of waste for sustainable development.
Evaluating the efficiency of Cyperus alternifolius on constructed wetland for the domestic wastewater treatment in the peri-urban area of Northern Vietnam
Authors: Thuy Anh Tran , Duc Ha Tran , Mai Huong Vi Thi
Published: July 2020

Constructed wetland (CW) is an ecological work that can treat wastewater in natural condition. Combining CW with other ecological wastewater treatment works can create a suitable low-cost treatment system for peri- urban areas. The climatic conditions in the Northern region are favorable for the growth of Cyperus alternifolius, one of the commonly planted tree in HFCW worldwide. Our study focuses on the growth of Cyperus alternifolius on HFCW to evaluate the removal efficiency of organic substances and nutrients (BOD5, N-NH4, N-NO3, P-PO4). The dynamical coefficients of decomposition of those matters were also identified. This research employed a wastewater treatment pilot with HFCW planted Cyperus alternifolius and other ecological facilities in a peri-urban area in the North of Vietnam. It was found out that Cyperus alternifolius grew well with a high growth rate. The growth of Cyperus alternifolius enhanced the conversion of organic substances (BOD5) and nutrients (NH4, NO3, PO4) with high decomposition kinetic coefficients. The kinetic coefficient (kBOD) of HFCW in this research was 0.214md−1 which is much higher than the recommendation of Design Standard TCVN 7957:2008. Domestic wastewater after being treated through CW satisfied level A of National technical regulation on domestic wastewater QCVN 14:2008/BTNMT.
Vibration testing for dynamic properties of building floors
Authors: Nguyen Tuan H A
Published: July 2020

The paper presents a comparison of testing methods and post processing techniques for modal properties of a fully furnished chipboard floor and an unfurnished prestressed concrete floor. A thorough modal testing required relocation of transducers among test setups to acquire multiple synchronous measurements of floor response due to heel drop excitation or shaker excitation. The comprehensive experimental data was processed by a specialised operational modal analysis software. On the other hand, a simple testing approach only required records of floor response at a single point due to heel drop. The measured response can be easily analyzed using simple procedures of structural dynamics. Whilst valuable information about the floor modal properties including the mode shapes was obtained using the sophisticated approach, the uncomplicated single-point heel drop test was found to provide reasonably accurate evaluation of natural frequencies and damping ratios for both of the test floors, which verifies the attractiveness of the simple technique. Based on experimental results, both of the floors would be considered as low-frequency floors by commonly used guidelines on human-induced floor vibrations. Furthermore, the effect of fit-out conditions and construction materials on the huge discrepancy between damping values of the two floors was also observed.
Experimental research of service actions influence on elastomeric bearings elastic properties
Authors: Shuvalov Aleksandr , Safina Larisa , Kovalev Mikhail
Published: July 2020

The article includes results of shear test of rubber-metal seismic insulators (elastomers) for different service actions. Research shows influence of low temperatures, material aging and cyclic loads on horizontal stiffness and shear modulus of elastomers. Tests were carried out according to existing Russian and foreign regulatory documents. An insignificant decrease in elastic properties of elastomers is seen after aging and cyclic loading. Influence of low temperatures increases stiffness of elastomers by 23%.
Method of effective parameters for calculations of turbulent swirling flows in engineering constructions
Authors: Akhmetov Vadim
Published: July 2020

The presented article is devoted to the application of the effective parameter method for calculating vortex structures in a turbulent swirling flow. The Navier-Stokes system of equations is used to study flow hydrodynamics, in which the Reynolds number and the swirl ratio are determined based on the concept of turbulent viscosity. The obtained solutions are compared with experimental data.
Dynamic stability and vibrations of thin-walled structures considering heredity properties of the material
Authors: Khudayarov Bakhtiyar , Turaev Fozilzhon , Vakhobov Valizhon , Gulamov Otabek , Shodiyev Sa’dulla
Published: July 2020

Dynamic stability and vibrations of thin-walled structures, taking into account the heredity properties of the material are considered in the paper. Mathematical models were constructed in a two-dimensional statement, using the Karman theory of plane plate strains and A.A. Ilyushin aerodynamic theory. When realizing the physico-mechanical properties of the material of the object, the systems of integro-differential equations (IDE) in partial derivatives with the corresponding initial and boundary conditions are taken as mathematical models of the problems under consideration. The obtained nonlinear partial IDEs using the Bubnov-Galerkin method under considered boundary conditions are reduced to solving systems of nonlinear ordinary IDEs with constant or variable coefficients with respect to the time function. The integration of equations obtained using the polynomial approximation of the deflections was carried out by a numerical method based on the use of quadrature formulas. Based on this method, an algorithm for the numerical solution of the problem was developed suitable for all viscoelastic and elastic elements of thin-walled structures of plate type.
Force properties of longitudinal interaction of the underground pipeline with soil
Authors: Ismoilova Sabida , Loginov Pavel , Khamidov Saidjon , Akbarov Nodirbek , Kumakov Jakhongir
Published: July 2020

The reliability of underground trunk pipelines, in most cases, is estimated based on their strength. When determining the strength of underground pipelines under seismic effects, it is necessary to take into account the forces of pipe-soil longitudinal interaction (the friction force) in calculations. Currently, linear relationships are used to describe the longitudinal interaction forces, where the interaction force is determined depending on the value of the pipe displacement relative to soil. The dependences of the interaction forces on the seismic stress state of soil are not taken into account at all. The paper shows that the interaction forces on the contact surface of an underground pipeline with soil are complex in nature and depend on the wave parameters in soil and in the pipeline itself. Based on the numerical results of solving one-dimensional unsteady-state coupled wave problems for the interacting system “underground pipeline-soil”, the pattern of changes in interaction forces on the pipeline-soil contact surface are determined. It was found that an account for static and dynamic soil pressure normal to the contact surface leads to quantitatively different results than when only static pressure is considered. It is shown that when solving the reliability problems of underground trunk pipelines under seismic effects, first it is necessary to take into account the dynamic stress-strain state of soil in the vicinity of the pipeline.
Forced vibrations of high-rise buildings
Authors: Khudainazarov Sherzod , Mavlanov Tulkin , Qosimov Jakhongir , Nurova Oliya
Published: July 2020

Studies were conducted to analyze the behavior of a high-rise structure on various kinematic effects, taking into account the real geometry, dissipative and nonlinear properties of the structure material. A generalized approach was developed for the dynamic calculation of high-rise structures, and the frequency response characteristics at various points of the structure were built. It was found that nonlinear properties are manifested when the impact can cause significant strain in the structure. This applies not only to the magnitude of the impact intensity, but also to its frequency content. If a non-linearly elastic strain of the material is manifested in the structure, then this leads to a decrease in the amplitudes of points displacements and to an increase in oscillation period compared to a linearly elastic structure under similar kinematic effects.
Evaluating the cable tension results by lift-off and vibration method in Viet Nam
Authors: Duc thi Thu Dinh Nguyen , Huu Hung Nguyen
Published: July 2020

The tension force value in cable of cable stayed bridge is the importance problem and necessary to control in design and service stage. The tension force value in cable is adjusted to ensure the internal force distribution of the structure is most reasonable and to ensure the camber, deflection or general deformation of the entire bridge. This tension adjustment has been performed and verified on many normal cable-stayed bridges. The cable-stayed bridge with more than 2 towers and 3 spans which is the trend of choice in the world as well as in Vietnam with beautiful architectural styles and suitable for use in difficult or limited conditions by topography, this verification is very limited. Recently, Bach Dang cable stayed bridge with 3 towers and 4 spans has opened for service in Viet Nam in Septemper, 2018, the authors have had the opportunity to approach the project and conduct tension measurements in cables by using the vibration analysis method at the time before project has opened for service. In order to evaluate the accuracy of the measurement results, the paper compares the results of tension force in cables that analyzed from measured by vibration method with the values of tension in cables that are directly measured by the lift-off method. These results are also compared with the results in design stage when analysing of bridge structure on software.