THE WATER-DEMAND AND GAP-VOLUME OF AGGREGATE FOR FERROCEMENT

In designing concrete based on paste saturation we should know the water-demand of cement, aggregate and the Gap-volume of aggregate mixture. The water-demand assures the consistency of fresh concrete and the cement-setting. The paste saturated concrete can be designed if the Gap-volume of aggregate is known. The experimental results of the author in this investigation shows such analytical relationships from which the water-demand and the Gap-volume of aggregate can easily be determined for the case of the gradually and continuously graded aggregates with maximal particle size (D = 1:2:4 mm)

Optimization of technological parameters in ultrasonic welding of the polypropylene fabric using Taguchi and FCCCD methods

Ultrasonic welding is a welding method that has been applied for welding nonwoven fabrics, with many advantages such as fast speed, high reliability, easy automation and especially less pollution to the environment. This paper studies the optimization of technological parameters in the welding process such as welding time, pressure, and weld shape on the breaking strength of ultrasonic welding of Polypropylene (PP) nonwovens. To evaluate the influence level and find the reasonable technological parameters domain in the paper, the Taguchi method is used in combination with the face-centered central composite design (FCCCD) response surface method. The research results have determined the regression equations used to calculate the breaking strength for each weld shape as well as the optimal domain for the main technological parameters, ensuring the breaking strength of the weld. There are different degrees of influence of technological parameters (shape of the weld zone, welding time and welding pressure) on the breaking strength of ultrasonic welds. Among them, the influence level of welding time t is 45.31 %, the weld shape is Pattern 2 with the rate of 30.03 %, and the welding pressure is 24.66 %. Carrying out a verification test with the welding parameters: t=1.6 s, p=3.1 kgf/cm2, two patterns ( Pattern 2 and Pattern 3), the result of breaking strength for patterns was achieved. Pattern 2 has a difference of 1.19 % between the regression equation results and the actual experimental results, while the figure for Pattern 3 is 0.77 %. From these results, it is possible to select the appropriate technological parameters for ultrasonic welding equipment when processing products from nonwoven fabrics to ensure the highest quality and productivit

Long-term loading examinations in connection with the law of linear creep

The failure process of concrete is usually described by the relative volume change function. The initial part of this function is constant. Balázs has named the upper limit of the constant part sigmaka (lower critical stress). His hypothesis is that, until this point is valid the law of linear creep. With the reviewed pre-experiments we examined the validity of this hypothesis. Due to this reason high strength concrete was long-term loaded up to 30; 50; 62 and 75% of the prism strength and the properties of the concrete were examined. According to the experiment the law of linear creep is probably valid until 0.50R/Rc,pr value, but it has to be proved by further experiments

Adaptation To Salinity Intrusion For Rice Farming Household In The Vietnamese Mekong Delta

Agriculture has considerably been affected due to the increased salinity in recent years in the Vietnamese Mekong Delta (VMD). The saline intrusion has increasingly caused problems to irrigation management, making it impossible to sustain the desired crop productivity. Rice farming are actually the most vulnerable as they have limited adaptive capacities and are more dependent on water for food production and other economic activities. This paper aims to understand how rice farming households responded to impacts of saline intrusion in the VMD, focusing the adaptive capacity and adaptation to saline intrusion at household level. The study showed that most rice farming households perceived the impacts of saline intrusion on their production activities, but only a few households prepared for adaptation options. Their decisions were not based on long-term saline intrusion impacts because households made decisions and changed farming practices due to economic factors and government policy support. The environment factors such as saline intrusion always came after economic and government policy factors. Government policy strongly affected production conditions of rice farming households through building irrigation, dyke and sluice gate systems. It means that change of production activities of rice farming households much more depended on government programs and development goals. Thus, households have fewer choices of production diversification away from rice farming

Investigation of botulism in free-range duck farming in the Mekong Delta, Vietnam

Background: One of the most common diseases in free-range ducks in the Mekong Delta is botulism. Botulism is a poultry disease caused by botulinum exotoxin of Clostridium botulinum. Aim: To evaluate the prevalence of botulism in free-range ducks in the Mekong Delta and the risk of infection by determining the presence of C. botulinum in the farming environment. Methods: Research was carried out on 200 duck flocks with 187,050 individuals raised freely in the fields in the provinces of the Mekong Delta, including An Giang, Can Tho, Hau Giang, and Kien Giang. The ducks were diagnosed with botulism based on clinical symptoms. To demonstrate the presence of botulinum neurotoxins and identify serotype, samples of serum and/or gut were analyzed by mouse bioassay. Samples of soil (n = 600), water (n = 600), crabs (n = 216), and snails (n = 400) were taken from the grazing regions for C. botulinum analysis by PCR assay. Results: There were 1.19% (2,235/187,050) free-range ducks in the Mekong Delta positive for botulism. Clinical symptoms of botulism including limberneck, drooping eyelids–enlarged pupils, and leg paralysis were prevalent across free-range ducks, with the frequency of 87.92% (1,965/2,235), 90.07% (2,013/2,235), and 79.78% (1,783/2,235), respectively. The lesions of pulmonary edema–hemorrhage, hemorrhagic liver, and gas-producing intestines were common, accounting for 86.19% (362/420), 95.48% (401/420), and 92.14% (387/420), respectively. Botulin toxin type C was found in a considerable number of serum samples, accounting for 40.48% (51/126). Meanwhile, the percentage of serum samples containing botulin toxin types E and D was 28.57% (36/126) and 25.40% (32/126), respectively. Clostridium botulinum was detected in the farming environment specifically 17.5% (105/600) in soil, 19.67% (118/600) in water, 8.33% (18/216) in crabs, and 3.00% (12/400) in snails. Conclusion: The free-range ducks in the Mekong Delta were at high risk of botulism because of the latent presence of C. botulinum in the farming environment

DYNAMICS OF PREDATOR-PREY POPULATION WITH MODIFIED LESLIE-GOWER AND HOLLING-TYPE II SCHEMES

Joint Research on Environmental Science and Technology for the Eart

Regional Integration Of Cham Muslims In The Mekong Delta

An Giang province is located in the Mekong Delta of Vietnam, recognized as Vietnam’s Mecca for large Muslim population in Vietnam. This paper introduces the root of the Cham (Sunni) Muslims living in this southwestern part of Vietnam. The historical research and documentary research (in which relevant historical documents and articles were selected to review and comment) were utilized in the study. The paper shows some differences between the Cham Muslims in this region and the Hindu Chams (Balamon). More importantly, this paper indicates that the Chams in the Mekong Delta have had more mobile ways of life and a more highly regional integration in the ASEAN Community and a larger Muslim world rather than other Cham groups in Vietnam

OPERATING SYSTEM FOR WIRELESS SENSOR NETWORKS AND AN EXPERIMENT OF PORTING CONTIKIOS TO MSP430 MICROCONTROLLER

Wireless Sensor Networks (WSNs) consist of a large number of sensor nodes, and are used for various applications such as building monitoring, environment control, wild-life habitat monitoring, forest fire detection, industry automation, military, security, and health-care. Each sensor node needs an operating system (OS) that can control the hardware, provide hardware abstraction to application software, and fill in the gap between applications and the underlying hardware. In this paper, researchers present OS for WSNs and an experiment of porting contikiOS to MSP430 microcontroller which is very popular in many hardware platforms for WSNs. Researchers begin by presenting the major issues for the design of OS for WSNs. Then, researchers examine some popular operating systems for WSNs including TinyOS, ContikiOS, and LiteOS. Finally, researchers present an experiment of porting ContikiOS to MSP430 microcontroller. Wireless Sensor Networks (WSNs) terdiri dari sejumlah besar sensor nodes, dan digunakan untuk berbagai aplikasi seperti pemantauan gedung, pengendalian lingkungan, pemantauan kehidupan habitat liar, deteksi kebakaran hutan, otomatisasi industri, militer, keamanan, dan kesehatan. Setiap sensor nodememerlukan sistem operasi (SO) yang dapat mengontrol hardware, menyediakan abstraksi hardware untuk aplikasi perangkat lunak, dan mengisi kesenjangan antara aplikasi dan hardware. Dalam penelitian ini, peneliti menyajikan SO untuk WSNs dan percobaan dari port contikiOS untuk MSP430 mikrokontroler yang sangat populer di platformhardware untuk WSNs. Peneliti memulai dengan menghadirkan isu utama yaitu desain SO untuk WSNs. Lalu, penelitimemeriksa beberapa sistem operasi populer untuk WSNs, termasuk TinyOS, ContikiOS, dan LiteOS. Akhirnya penelitimenyajikan sebuah percobaan dari port ContikiOS untuk MSP430 mikrokontroler

A Fuzzy LQR PID Control for a Two-Legged Wheel Robot with Uncertainties and Variant Height

This paper proposes a fuzzy LQR PID control for a two-legged wheeled balancing robot for keeping stability against uncertainties and variant heights. The proposed control includes the fuzzy supervisor, LQR, PID, and two calibrations. The fuzzy LQR is conducted to control the stability and motion of the robot while its posture changes with respect to time. The fuzzy supervisor is used to adjust the LQR control according to the robotic height. It consists of one input and one output. The input and output have three membership functions, respectively, to three postures of the robot. The PID control is used to control the posture of the robot. The first calibration is used to compensate for the bias value of the tilting angle when the robot changes its posture. The second calibration is applied to compute the robotic height according to the hip angle. In order to verify the effectiveness of the proposed control, a practical robot with the variant height is constructed, and the proposed control is embedded in the control board. Finally, two experiments are also conducted to verify the balancing and moving ability of the robot with the variant posture

Stabilization for equal-order polygonal finite element method for high fluid velocity and pressure gradient

This paper presents an adapted stabilisation method for the equal-order mixed scheme of finite elements on convex polygonal meshes to analyse the high velocity and pressure gradient of incompressible fluid flows that are governed by Stokes equations system. This technique is constructed by a local pressure projection which is extremely simple, yet effective, to eliminate the poor or even non-convergence as well as the instability of equal-order mixed polygonal technique. In this research, some numerical examples of incompressible Stokes fluid flow that is coded and programmed by MATLAB will be presented to examine the effectiveness of the proposed stabilised method