bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pilot studies on the river water treatment using coagulation-UF membrane filtration and direct UF membrane filtration
Authors: Nakanishi H , Yabuno Y , Nishikawa T , Yasui T , Pham A T , -A Nguyen V 
Published: July 2020

Abstract
The pilot tests of UF membrane filtration for river surface water were carried out with coagulation as a pre-treatment (test 1) and without coagulation (test 2). Both UF membrane filtrate water of the test 1 and the test 2 met drinking water quality standard in Vietnam. Additionally, the TMP and the filtration flow rate were kept stably during test periods without changes in operation conditions although the river water turbidity was varied due to heavy rain. It was indicated that the water treatment system can be simple by skipping coagulation and/or sedimentation as pre-treatments. The filtration flux of the test 1 and the test 2 were 138 L/m2 h and 93 L/m2 h, respectively. The flux was higher than the reported reference value indicating that the module number of modules required for the water treatment plant can be reduced by using the FG module. The test data of the test 2 was theoretically analysed by the equations based on Darcy’s low. The estimated TMP correlated highly with measured value (R2=0.71). The optimized parameters were used for the simulation of the operation. The simulation results indicated that the TMP before backwashing is increased around 35 kPa when the river water turbidity increased up to 500 NTU. It was indicated that the CIP interval should take into account the TMP increasing by turbidity variation.
Scenarios for treatment of sewage sludge from municipal wastewater treatment plants in Hanoi towards energy efficiency and resource recovery
Authors: Hoai An Vu Thi , Viet Anh Nguyen , Minh Thanh Vu Thi 
Published: July 2020

Abstract
Wastewater treatment plants (WWTPs) generate significant amount of sewage sludge (SS). Besides, faecal sludge (FS) generated from popularly existing septic tanks in cities need also adequate treatment. Selection of appropriate sludge treatment options is among most challenging wastewater management issues for fast growing cities. The case study has selected the central part of Hanoi city, with expected population of 2,145,437 persons by 2030, total design capacity of WWTPs 588,300 m3/day, whereas different options of SS and FS management were analysed. The calculation results shown that an energy required for operation of sludge treatment processes in scenarios 2, 3 and 4 could be fully self-sufficient. Besides, with total energy demand for operation of WWTPs was of 311,799 kWh/day, 21.3% (scenario 2), 99.3% (scenario 3) or 71.3% (scenario 4) of demand could be covered by remaining biogas produced from anaerobic co-digestion of SS and FS. A conventional SS treatment process, dewatering by centrifuge and dumping dewatered sludge to the landfill (scenario 1) did not generate any energy but required an energy of 17,371 kWh/day for SS treatment and dumping. Anaerobic co-digestion of SS, FS, other organic fractions, can be a promising sludge management solution aiming at energy efficiency and resource recovery.
Influence of weather conditions on energy consumption of controlled blowers at WWTP
Authors: Ustiuzhanin Andrei , Chizhik Konstantin , Bazhenov Victor 
Published: July 2020

Abstract
The object of analytical research are controlled air blower units of wastewater treatment plants (WWTPs) for wastewater utilities with pneumatic aeration systems for biological processes, based on oxygen consumption. The goal of analytical research is accounting and estimation values of temperature, relative humidity, atmospheric pressure for energy consumption by controlled air blowers. The system of equations is proposed for the joint solution: 1st equation - according to the Guide to Meteorological Instruments and Methods of Observation; 2nd equation - modification for determining the energy consumption for the blower unit P wire in kW. These form the analysed mathematical model with the following results of study. Fluctuations in the full range of operating temperatures leads to a change in power consumption in the range –14.9 to 19.9%. Fluctuation of atmospheric pressure in the full range leads to a change in power consumption in the range from –3.4 to 3.7%. Relative humidity affects power consumption only in combination with high temperature (between 20-40°C the maximum influence of relative humidity is 0.6-3.3%). The combined influence of all three parameters in the full range is from –9.2 to 11.2%. All presented data are supplied also for the range of average values.
Innovative unit for water treatment
Authors: Govorova Zhanna , Semenovykh Vasiliy , Govorov Oleg 
Published: July 2020

Abstract
The main pollutants of groundwater sources are compounds of iron, manganese and and dissolved gases (carbon dioxide, hydrogen sulphide). Requirements to small capacity groundwater treatment units specified by a group of consumers were reviewed in this work. Various aeration units are used at the first stage as a part of simplified aeration method in deferrization process flow chart. There is offered an innovative unit which combines several processes, such as aeration, degassing, filtering through the layer of expandable polystyrene foam. The unit allows excluding additional aeration units, washing pumps and flush water storage tanks, as well as to intensify the aeration-degassing process, increase treatment efficiency and provide specified requirements. The article contains data on modular units with capacity up to 1 m3/h, their operating principle and the laboratory equipment used, as well as the aeration and degassing processes analysis results. When the level of dissolved oxygen in groundwater reaches 1.24-1.64 mg/l and free carbon dioxide - 46.8-50 mg/l outbound of the aeration units dissolved gases are blown out (up to 36%), the concentration of oxygen increases up to 7 mg/l. which is enough for an effective water deferrization process. At the same time, this process takes less time up to 2.7) in the aeration unit rather than in the aeration column.
Investigation of groundwater recharge mechanism for sustainable urban water system planning and management in Hanoi city
Authors: Thi Viet Nga Tran 
Published: July 2020

Abstract
Seasonal variation of water levels and water quality of groundwaters and ponds was investigated to illustrate the recharge mechanism and seasonal effects of groundwater in Hanoi suburbs. Water level monitoring data showed that the upper aquifer had a fluctuating water level (variation: 2.0 m) corresponding to heavy rains, representing a substantial impact by infiltration of rainwater from the surface and perhaps pond water. In the area with less permeable surface, there was small response to rainy events, suggesting that the ground water levels were governed by a regional scale groundwater flow. The stable isotope ratios in pond waters had a clear seasonal change, in which isotopes were enriched throughout the dry season. In groundwater, isotope signatures indicated that the dominant sources had evaporation process. In studied areas, the isotope ratios in groundwaters and pore waters in the shallow soil (<25 m depth) were clearly heavier than that in the deep soil. Isotope results suggested that groundwaters close to the Red River are largely recharged by the river itself. In areas far from the river, surface waters having evaporation process (e.g., ponds and paddy fields) and the rainwater directly infiltrating from the surface mainly recharges the upper aquifer. The lower aquifer in inland locations would be recharged by lateral inflow, either from the Red River or surrounding mountains. The results revealed the recharge mechanism for groundwater budget which could contribute for the planning and sustainable development of urban water system in Hanoi City.
Proposal of a set of quantitative criteria for evaluating and classifying urban street flooding spots in Vietnam
Authors: Nguyen Viet-Phuong , Pham Tuan-Hung , Ung Thi-Thuy-Ha , Hoang Tung , Tong Ngoc-Tu 
Published: July 2020

Abstract
Street flooding in urban areas in Vietnam has always been a stress issue despite the municipal government’s investment in renovating and upgrading the drainage system. Until present, in order to evaluate and classify street flooding spots, the authorities have been applying the criteria specified in Document No. 338/BXD-KTQH issued by Ministry of Construction dated March 10, 2003. Despite their certain efficiency and value, the current criteria have not shown how the flooding spots affect traffic and not clarified how to measure or determine the parameters as a basis for flood classification, etc. Therefore, the Ministry of Construction has ordered the research team to develop a set of quantitative criteria for evaluating and classifying the street flooding spots in Vietnam. Accordingly, this paper presents the results of the study in contribution to more effective management of urban infrastructure.
Optimal use of solar collectors in small-scale districts
Authors: Zajacs Aleksandrs , Borodiņecs Anatolijs , Neviero Igors 
Published: July 2020

Abstract
It is vitally important to choose a sustainable, rational heating system and, in view of the trends of the European Union, as well as a system with lower harmful emissions. This work explores the efficiency of solar collector use in district heating systems. The wide application of solar panels allows to improve it overall efficiency by utilized exceed heat into district heating systems. Especially in small scale systems. Solar collectors are a type of renewable energy that is not only an ecological solution for heat generation but also increases energy independence. Within the framework of the work, a working specifics of district heating system has been studied, where different types of solar collectors are used for partial heat energy supply. By changing the area of solar collectors for constant heat consumption, the results on efficiency and effectiveness of use were obtained and analysed. The TRNSYS energy simulation tool was used for dynamic simulations. Researches, results and conclusions made in this research can be used in the work of engineers and designers to improve the existing centralized heat supply systems and to anticipate possible challenges in the newly built.
Filtration of a highly concentrated suspension in a porous medium
Authors: Kuzmina Liudmila , Osipov Yuri 
Published: July 2020

Abstract
The problems of filtration in porous media are in demand when strengthening foundations and building waterproof walls in rocks. Deep bed filtration of a highly concentrated monodisperse suspension in a homogeneous porous medium with size-exclusion particle retention mechanism is considered. When filtering a suspension in a porous medium, some solid particles get stuck on the porous frame and form a deposit. The concentration of suspended particles injected at the porous medium inlet decreases when moving from inlet to outlet. The mathematical model for a highly concentrated suspension in a porous medium assumes a nonlinear dependence of the deposit growth rate on the concentration of suspended particles. The exact solution to the filtration problem in implicit integral form and the Riemann invariant relating the concentrations of suspended and retained particles are obtained. The problem is solved for a linear filtration function and a general nonlinear concentration function. An asymptotic solution is constructed near the concentrations front of suspended and retained particles. It is shown that the asymptotics is close to the exact solution, the error decreases with increasing order of asymptotic expansions. The asymptotic solution explicitly defines the dependence of the solution on model parameters and can be used to solve the inverse filtration problem.
Reinforced concrete structures stress-strain state strengthen with composite materials
Authors: Telichenko Valery , Rimshin Vladimir , Ketsko Ekaterina 
Published: July 2020

Abstract
In recent years, innovative strengthening of reinforced concrete structures for industrial and civil use by external reinforcement based on carbon fiber has been widely used. However, there are only a few application examples of this amplification technology in the water treatment and sanitation facilities construction and rehabilitation. Based on experimental and practical data, composite amplification systems provide significant results both when working structures in normal conditions, and when they are in aggressive environments. Compared to conventional structural materials, carbon fiber-based composite materials have higher strength, significant fatigue resistance, high elastic modulus, chemical and thermal resistance.This article discusses the calculating method for strengthening reinforced concrete crossbars for coating the construction of an underground purified drinking water reservoir reinforced with composite materials. Based on the calculation methods, the reinforcing feasibility is substantiated. This work was carried out according to the results of a crossbars survey. In order to achieve these goals, a survey was made of the crossbars of the treated drinking water tank, the actual effective loads on the reinforced concrete crossbars were determined, the need to strengthen the examined structures according to the results of calibration calculations was determined, recommendations were developed to strengthen the examined structures of the reservoir construction. A survey of the structures of the structure, as well as an assessment of their technical condition, was carried out taking into account the requirements of current regulatory documents.
Analysis of numerical model parameters for dry-mixed soil-cement composite with high content of organic matter
Authors: Jendrysik Klaudia , Rybak Jarosław 
Published: July 2020

Abstract
Numerical modelling of geotechnical issues requires basic subgrade parameters which need to be introduced into the program. The best way of collecting such information is to commission a series of tests. Defining the parameters of the material gained when admixtures are introduced into existing soil becomes problematic. Basic strength parameters can be found from trial batches of quasi-concrete composite, however they do not ensure the full spectrum of necessary data. Numerical programs often require more parameters from the user and these data are dependent on the strength hypothesis assumed. In this situation, one of possible solution is to run a inverse analysis. The paper provides exemplary procedure of iterative determination of cohesion, internal friction angle and Poisson’s ratio for a soil-cement sample obtained in dry mixing procedure. The original soil contained relatively high content of organic parts in dry mass. The analysis was made for hypothesis of Coulomb-Mohr and Drucker-Prager. The conclusions drawn from performed studies give some recommendations, but, due to possible soil heterogeneity, emphasise the need for further studies.
Underground pipeline reliability under longitudinal impact load
Authors: Sultanov Karim , Khusanov Bakhtiyar , Rikhsieva Barno 
Published: July 2020

Abstract
The paper presents the results of numerical solution obtained by the modified finite difference method according to the Wilkins scheme, to a two-dimensional unsteady-state problem of the plane shock wave propagation in an underground elastic pipeline, interacting with surrounding soil. Soil is considered to be an undeformable body moving relative to the pipeline at a given velocity. The value of the friction force depends on radial stress in the pipeline, determined by numerical solution to the problem. Changes in longitudinal and radial stresses over time and pipeline length, of velocity and displacements for fixed sections of the pipeline are obtained. Two times increase in values of longitudinal and radial stresses was detected in the case of active Coulomb friction at the pipeline-soil contact. The increase in stress values occurs due to the friction force acting in the direction of wave propagation. At significant values of the friction force on the outer surface of the pipeline, the hypothesis of flat sections is fulfilled for all its sections. This result justifies the consideration of similar problems of underground pipelines earthquake resistance in a one-dimensional statement. The results also make it possible to identify the mechanisms of the stress state formation in an underground pipeline interacting with soil, which can be used in seismic resistance calculation of underground trunk pipelines.
Reliability-based design optimization of steel frames using direct design
Authors: Truong Viet-Hung , Ha Manh-Hung 
Published: July 2020

Abstract
This paper presents an effective method for reliability-based design optimization (RBDO) of steel frames by combining direct design using nonlinear inelastic analysis, an improved importance sampling technique for structural failure probability analysis, and an improved differential evolution (DE) algorithm for optimization. The nonlinear inelastic analysis using the beam-column approach is used to capture the second-order effects and the inelastic behavior of structures. An improved importance sampling technique based on nonlinear inelastic analysis of the structure is employed that significantly reduces the number of structural analyses required for calculating the structural failure probability. An improved DE algorithm, which can effectively eliminate the redundant structural analyses for objective function evaluation, is utilized. A six-story space frame is studied to demonstrate the computational efficiency of the proposed method.
Analysis of adhesion factors of the external reinforcement and base surface of the bent concrete element
Authors: Simakov Oleg , Simakov Aleksandr 
Published: July 2020

Abstract
The development of reinforcement technology for existing reinforced concrete structures requires more accurate and careful consideration of various reinforcement parameters. Refinement of the calculation theory, coefficients, and the introduction of additional criteria make possible to strength structures with greater efficiency. One of the ways to increase the effectiveness of external reinforcement accounting, in fact, increasing the calculated value of the load-bearing capacity of the reinforced section, is consideration the anchoring of the reinforcement element. Currently used methods for calculating the strength of bent elements take into account the coupling of external reinforcement with the surface of the reinforced element by limiting deformations. At the same time, if it is possible to take into account the anchoring of the external reinforcement, both the calculated and the actual bearing capacity of the reinforced element is increase. There’s an analyzes the factors that determine the anchoring of the external reinforcement, which affect the load-bearing capacity of the reinforced normal section of the reinforced concrete element. The analysis is based on previous experimental studies, as well as numerical modeling of the distribution of shear forces. The simulation was performed on a single-span reinforced concrete beam with a hinged support. The numerical simulation took into account the nonlinear nature of the deformation of reinforced concrete (reinforced element), as well as the binding external reinforcement. The work of the outermost reinforcement (carbon fibers) was considered linear, since the graph of deformation of the carbon fiber is almost a straight line before destruction.
Bearing capacity of the facade system under temperature effect
Authors: Tusnina Valentina 
Published: July 2020

Abstract
Hinged facade systems are the external enclosing structures of buildings. These systems are subject to a range of loads, including temperature effects. Temperature effects significantly affect the structural bearing capacity. This article presents the results of experimental and theoretical studies of the bearing capacity of a hinged facade system, taking into account the influence of temperature load on the example of a design with gear assemblies of flexible fastening of facing panels. An assessment of the stress-strain state of nodal structural elements is given. A comparative analysis of the strength and deformability of suspended facade systems with flexible and rigid joints of structural elements is given. On the basis of experimental studies, it was found that to ensure free movement during temperature influences in riveted joints, it is necessary to place the rivet “head” in the oval hole and press the rod into the round hole. Assessment of the stress-strain state of the connecting elements in flexible nodes showed that stresses from the temperature load arising in the supporting brackets are very small and amount to ∼ 1.5% of the maximum allowable stresses. This allows us to conclude that these stresses can be ignored.
Calculation of the settlement of pile foundations taking into account the influence of soil liquefaction
Authors: Ter-Martirosyan Armen , Anh Le Duc 
Published: July 2020

Abstract
Pile foundations are considered one of the most common foundation solutions for the construction of buildings and structures in difficult geotechnical conditions, including in seismic areas. However, during earthquakes specific processes often occur that negatively affect the interaction of piles with the surrounding soil. Soil liquefaction is one of the most difficult problems in geotechnics. Many historical cases show that buildings and structures on pile foundations are collapsed completely when the surrounding soil liquefies. One of the reasons is the increase in settlement of the foundation after soil liquefaction.
Unlike the liquefaction potential assessment, or liquefaction-induced settlement of structures on shallow foundations, which are discussed by many researchers, the settlement of pile foundations after soil liquefaction has not been studied extensively. This paper presents the calculation of the settlement of pile foundations in different cases, with and without taking into account the influence of soil liquefaction, based on the hypothesis that the additional downward loads due to self-compaction of the liquefiable soil layers have an effect on piles. The analysis method in this study refers to the finite element method via PLAXIS 3D software. Finally, a brief comparison of the calculation results in the different considered cases is presented. The comparison shows how much the foundation settlement can increase if the influence of soil liquefaction is taken into account based on the suggested hypothesis. This paper provides a useful calculation and importance of further researches of liquefaction-induced settlement of pile foundations for seismic design.