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Trend Significance Levels of Rain Onset and Cessation and Lengths of the Wet and Dry Seasons in Epe, Lagos State, Nigeria 尼日利亚拉各斯州埃佩地区降雨开始和停止以及湿季和旱季长度的趋势显著性水平
Pub Date : 2021-09-01 DOI: 10.7454/MST.V25I2.3953
A. A. Alli, O. Omofunmi
This study aims to reduce crop failure resulting from a dry spell, which is the first occurrence of unsustainable rainfall that deceives farmers into planting. Thus, trends need to be tested using hypothesis, kurtosis, and other statistics to analyze the risks associated with unstable planting calendars and their possible mitigation strategies. The daily rainfall data from 1982 to 2018 were obtained from the archive of NASA/POWER SRB/FLASH, and the research location is Epe, Lagos State, Nigeria, which lies at latitude 6.585° N and longitude 3.962° E. Microsoft Excel was used to perform the tests. Results show that the null hypothesis of no trend in the distribution was rejected on the basis of the fact that the probability value (p = 0.00) is less than the significance level (α = 0.05). The mean onset and cessation dates are March 27 and October 18, with skewness values of −0.63 and 11.02, respectively. Rain onset and cessation that occur from February 12 to April 27 and from September 28 to November 28, respectively, are safe with low risks of dry spell. Moreover, drought and dry spell were most probable in years that experienced a shorter length of wet season than dry season.
这项研究旨在减少干旱造成的作物歉收,干旱是首次出现的不可持续降雨,欺骗农民种植。因此,需要使用假设、峰度和其他统计数据来检验趋势,以分析与不稳定种植日历相关的风险及其可能的缓解策略。1982 - 2018年的日降雨量数据来源于NASA/POWER SRB/FLASH档案,研究地点为尼日利亚拉各斯州Epe,位于北纬6.585°N,东经3.962°e,使用Microsoft Excel进行测试。结果表明,由于概率值(p = 0.00)小于显著性水平(α = 0.05),否定了分布无趋势的原假设。发病和停止的平均日期为3月27日和10月18日,偏度值分别为- 0.63和11.02。2月12日至4月27日和9月28日至11月28日分别为降雨和停雨,是安全的,干旱风险低。此外,干旱和干旱最可能发生在雨季比旱季短的年份。
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引用次数: 0
Effect of drying method on compressive strength of straw-based thermal insulations 干燥方式对秸秆基绝热材料抗压强度的影响
Pub Date : 2021-05-19 DOI: 10.31448/MSTJ.03.01.2020.108-116
Olivér Fenyvesi, Dániel Csanády
Most of the thermal insulations in the construction industry market based on fossil raw material or need a huge amount of production energy. Nowadays, sustainable thermal insulation products are more popular, and the demand for these products on the market is increasing. Some of them reach the main material properties of artificial ones but usually not all. Today the reaction to fire is another big challenge in this field. In many cases, producers use chemicals that can increase fire resistance, but on the other hand, increase the environmental impact of insulations too. It is also hard to find a binder which provides proper mechanical parameters and durability and is environmentally friendly too. During our scientific research on environmentally friendly thermal insulation materials, which is running for 4 years, we found that silicate-based adhesives meet many of these criteria mentioned above. In this article, the mechanical properties of straw-based insulation bonded with silicate binder were investigated. The effect of conventional and microwave drying on compressive strength were compared to found the optimal hardening process of binders. During the experiments, straw was applied in a natural state, natural stem length distribution and without microstructure and surface modification. The used binder is a simple silicate-based binder (potassium silicate) without any modification agent. Conventional drying needs a longer time, and during it, many cracks form in the early age of the hardened binder. It is because of shrinkage and the differences in the rigidity of the binder along its cross-section. Besides, the straw stems swell when exposed to moisture (from binder), and after drying they shrink, which decreases the quality of the bond between stems and binder. The microwave drying evenly heats the various points of the specimen, so it is not generated such big differences in shrinkage. The contact between stems and binder are also better. Due to these effects, the microwave dried specimens reached the limit required for step resistance, and they had three-time higher average compressive strength than we got by the conventional drying of the same raw material.
建筑行业市场上的保温材料大多以化石原料为基础或需要大量的生产能源。如今,可持续保温产品越来越受欢迎,市场上对这些产品的需求也越来越大。其中一些达到了人造材料的主要材料性能,但通常不是全部。今天,对火灾的反应是该领域的另一个重大挑战。在许多情况下,生产商使用的化学物质可以提高防火性能,但另一方面,也增加了绝缘材料对环境的影响。也很难找到一种粘合剂,既能提供适当的机械参数和耐久性,又对环境友好。在我们对环保保温材料进行了4年的科学研究中,我们发现硅酸盐基胶粘剂符合上述许多标准。研究了硅酸盐粘结剂粘结稻草基绝热材料的力学性能。比较了常规干燥和微波干燥对粘结剂抗压强度的影响,找到了粘结剂的最佳硬化工艺。试验期间,秸秆在自然状态下施用,茎长分布自然,不进行微结构和表面改性。所使用的粘结剂是一种简单的硅酸盐基粘结剂(硅酸钾),不含任何改性剂。常规干燥需要较长的时间,并且在此过程中,在硬化粘结剂的早期形成许多裂纹。这是由于收缩和粘结剂在其横截面上的刚性差异。此外,秸秆茎在接触水分时(来自粘合剂)会膨胀,干燥后会收缩,这降低了茎与粘合剂之间的粘合质量。微波干燥使试样各点受热均匀,故不会产生如此大的收缩率差异。茎杆与粘结剂之间的接触也较好。由于这些影响,微波干燥的样品达到了台阶阻力要求的极限,并且它们的平均抗压强度比我们通过常规干燥得到的相同原料高三倍。
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引用次数: 0
CONTENT MANAGEMENT SYSTEM FOR SCHOOL INFORMATION WEBSITE 学校信息网站内容管理系统
Pub Date : 2021-04-13 DOI: 10.47002/MST.V1I1.203
M. Yani, Fahrul Rizal, Muhammad Reza Padillah
The website is one of the digital information media used by schools to display their profiles so that they can be known by the public. Some SMP Negeri in Kota Samarinda do not yet have a website as a media or school information center. This could be due to difficulties in creating and on the website of each school. From these problems, in this study researchers innovated to create a Content Management System (CMS) for school websites, especially at SMP Negeri 29 Samarinda. Laravel PHP framework is used with the system development method is the Waterfall method.
该网站是学校用来展示他们的个人资料的数字信息媒体之一,以便让公众了解他们。哥打萨玛林达的一些地方自治团体还没有网站作为媒体或学校信息中心。这可能是由于在创建和创建每个学校的网站方面存在困难。针对这些问题,在本研究中,研究人员创新地为学校网站创建了一个内容管理系统(CMS),特别是在SMP Negeri 29 Samarinda。与Laravel PHP框架配合使用的系统开发方法是瀑布法。
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引用次数: 1
Static analysis of bond between prestressing strand and UHPC exposed to elevated temperatures 高温下预应力钢绞线与UHPC粘结的静力分析
Pub Date : 2021-01-28 DOI: 10.31448/MSTJ.03.01.2020.102-107
D. Čítek, J. Čech, P. Pokorný, J. Kolísko
This article deals with the numerical analysis of the bond of a prestressing strand with UHPC heated to elevated temperatures and subsequently cooled. Numerical analysis was performed with experimentally determined material properties of UHPC at a reference temperature of 20 °C and further after heating to temperatures of 200, 400 and 600 °C and subsequent annealing to normal temperature. The resulting deflection depending on the pulling force from the numerical analysis were compared with the experimental results. The results are used to configure the cement composite model for more demanding simulations of structures and load cases.
本文讨论了高温加热后冷却的预应力超高性能混凝土粘结的数值分析。对实验确定的UHPC材料在参考温度为20℃、加热至200℃、400℃和600℃并退火至常温下的性能进行了数值分析。将数值分析结果与实验结果进行了比较。结果用于配置水泥复合材料模型,以满足更苛刻的结构和荷载情况的模拟。
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引用次数: 0
Buckling length of reinforced concrete columns in non-sway constructions 无摇摆结构中钢筋混凝土柱的屈曲长度
Pub Date : 2021-01-28 DOI: 10.31448/MSTJ.03.01.2020.94-101
P. Dolny, P. Wilinski, Krzysztofiń Kamski
The paper presents a comparison of methods of determining the buckling length of reinforced concrete columns in non-sway frames. The comparison was made on the basis of guidelines issued by Poland some EU countries, USA and India. Differences in approaches and values of buckling length coefficients of columns calculated according to these guidelines are shown. An example of the calculation of column buckling length coefficients on selected multi-span, multi-storey non-sway frames is given.
本文比较了几种确定无侧摆框架中钢筋混凝土柱屈曲长度的方法。比较是根据波兰、一些欧盟国家、美国和印度发布的指导方针进行的。给出了根据这些准则计算柱的屈曲长度系数的不同方法和值。给出了选定的多跨多层无侧移框架的柱屈曲长度系数计算实例。
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引用次数: 0
Redesign of Product Packaging with Kansei Engineering: Empirical Study on Small-medium Enterprises in Indonesia 感性工学的产品包装再设计:印尼中小企业的实证研究
Pub Date : 2020-09-01 DOI: 10.7454/mst.v24i2.2990
A. Suzianti, A. Aldianto
Small-medium enterprises (SMEs) in Indonesia have been proven to be one of the important pillars of the national economy. Unfortunately, some problems hinder their development, and one of the critical problems is the quality of product packaging. The packages of SME products are considered poor, dirty, and unattractive. Packaging problem is one of the factors why consumers are less interested in buying and why SME products always lose in the competition with other products. This study discusses how to employ Kansei engineering to design better SME product packaging with a focus on psychological (affective) aspects. This research concludes that there are four components that represent consumers’ desires: Attractiveness, Robustness, Handy & Green, and Lightness. The final result of this research is the creation of four new designs for a product package that satisfies each of the above components.
印尼的中小企业已被证明是国民经济的重要支柱之一。遗憾的是,一些问题阻碍了他们的发展,其中一个关键问题是产品包装的质量。中小企业产品的包装被认为是劣质、肮脏和不吸引人的。包装问题是消费者购买兴趣降低的原因之一,也是中小企业产品在与其他产品的竞争中总是失败的原因之一。本研究探讨如何运用感性工学,以心理(情感)方面为重点,设计更好的中小企业产品包装。这项研究得出的结论是,有四个组成部分,代表消费者的愿望:吸引力,稳健性,方便和绿色,和轻便。这项研究的最终结果是为满足上述每个组件的产品包装创造了四个新的设计。
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引用次数: 2
Effect of Landfill Leachates on Some Water Quality Indicators of Selected Surface Water and Groundwater at Ilokun, Ado-Ekiti, Nigeria 垃圾渗滤液对尼日利亚阿多-埃基蒂Ilokun部分地表水和地下水水质指标的影响
Pub Date : 2020-09-01 DOI: 10.7454/mst.v24i2.3881
O. Omofunmi, A. Satimehin, A. Oloye, Okwunna M Umego
This study was conducted to examine the impact of dumpsites on the quality of groundwater and surface water. The water samples and leachates were collected from dumpsites in respective zones. The physicochemical properties of the samples were examined and determined in accordance with the standards of the American Public Health Association. Results indicated that the groundwater and surface water that are close to the dumpsites have an electrical conductivity of 385 and 245 Sd/cm, total dissolved solids of 168 and 128 mg/L, a turbidity of 4.6 and 22 NTU, a total alkalinity of 103 and 50 mg/L, a total hardness of 120 and 80 mg/L, Ca concentration of 44 and 14 mg/L, Mg concentration of 0.2 and 15 mg/L, SO4 concentration of 4 and 42 mg/L, Cl concentration of 38 and 16 mg/L, and NO3 concentration of 6 and 8 mg/L, respectively. Moreover, the water near the dumpsites had higher elevated physicochemical properties compared with those far from the dumpsites; in addition, they were significantly different (p ≥ 0.05). Hence, the closer the groundwater and surface water to the dumpsite, the greater the negative impact on the physicochemical properties of water. The pH concentration in leachate serves as an indicator for the age and mineralization status of dumpsites, and it influences the other chemical properties of the leachate. Furthermore, the pH concentration in leachate is inversely proportional to the concentration of Ca, Mg, and SO4 in the study area.
本研究旨在探讨垃圾场对地下水及地表水水质的影响。水样和渗滤液是在有关地区的弃置场收集的。样品的物理化学性质按照美国公共卫生协会的标准进行了检查和测定。结果表明,地下水和地表水的垃圾堆场里有导电性的385年和245年Sd /厘米,总溶解固体的168和128毫克/升,浊度为4.6,22南大,总碱度103和50 mg / L,总硬度120和80 mg / L, Ca的浓度44岁和14毫克/ L, 0.2毫克的浓度和15 mg / L,哌嗪浓度4和42 mg / L, Cl 38和16 mg / L,浓度和硝酸浓度的6和8 mg / L,分别。此外,垃圾场附近水体的理化性质明显高于远离垃圾场的水体;两组间差异有统计学意义(p≥0.05)。因此,地下水和地表水离垃圾场越近,对水的理化性质的负面影响越大。渗滤液的pH浓度是垃圾场年龄和矿化状况的指标,并影响渗滤液的其他化学性质。此外,研究区渗滤液pH浓度与Ca、Mg、SO4浓度成反比。
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引用次数: 0
Effect of PVDF-CA Ratio on Electrospun Membrane for Water–Oil Filtration Application PVDF-CA配比对电纺膜水-油过滤的影响
Pub Date : 2020-09-01 DOI: 10.7454/mst.v24i2.3845
M. W. Alias, I. I. Misnon, R. Jose
Oil spillage and generation of industrial water–oil wastewater mixture ignite a focus on filtration technology. Electrospinning technique provides a versatile route in producing tunable diameter and pores in nanofiber filtration membrane development. In this work, polyvinylidene difluoride (PVDF) and cellulose acetate (CA) electrospun membrane at different concentration ratios were synthesized for water–oil filtration application. The polymeric solutions were characterized using viscometer and conductivity testing, whereas the membranes were analyzed using contact angle, tensile test, scanning electron microscopy (SEM), and filtration testing of oil (dichloromethane). Conductivity test showed a decreased conductivity along with decrement of CA ratio in the polymeric solution. The viscosity results showed a rising trend along with the increment of CA in the polymeric solution along with the decrement of PVDF ratio. SEM result showed that all membranes had a fiber diameter range of 210–485 nm and pore size range of 235–856 nm. The tensile test showed a decreasing tensile strength as the ratio of PVDF in the electrospun membrane decreased. The membrane with PVDF-to-CA ratio of 90:10 showed optimum performance for water–oil filtration with a flux of 14,111 Lm −2 h −1 and oil recovery of 94%.
石油泄漏和工业水-油废水混合物的产生引起了人们对过滤技术的关注。静电纺丝技术为纳米纤维过滤膜的直径可调和孔径可调提供了一条通用的途径。本文合成了不同浓度比的聚偏二氟乙烯(PVDF)和醋酸纤维素(CA)电纺膜,用于水-油过滤。聚合物溶液通过粘度计和电导率测试进行表征,而膜则通过接触角、拉伸测试、扫描电子显微镜(SEM)和油(二氯甲烷)过滤测试进行分析。电导率测试表明,随着聚合物溶液中CA比的减小,电导率降低。黏度随聚合物溶液中CA含量的增加和PVDF比的降低呈上升趋势。SEM结果表明,所有膜的纤维直径范围为210 ~ 485 nm,孔径范围为235 ~ 856 nm。拉伸试验表明,随着聚偏氟乙烯(PVDF)在静电纺丝膜中含量的降低,拉伸强度逐渐降低。pvdf - ca比为90:10的膜具有最佳的水油过滤性能,过滤通量为14111 Lm−2 h−1,采收率为94%。
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引用次数: 0
Microstrip Filters: A Review of Different Filter Designs Used in Ultrawide Band Technology 微带滤波器:用于超宽带技术的不同滤波器设计综述
Pub Date : 2020-09-01 DOI: 10.7454/mst.v24i2.3903
Hussain Bohra, G. Prajapati
In this study, optimization techniques applied in designing microstrip bandpass ultra-wideband (UWB) filters are presented. Optimization based on various defected ground structure techniques, resonator designs, and type of dielectric materials is discussed. Microstrip bandpass filters implemented at UWB frequency bands used in wireless communication systems have key features to control frequency response in passband and stopband. Optimization techniques are studied to attain optimum performance of bandpass microstrip filters to ensure minimum insertion loss, high selectivity, compactness, sharp transitions at cut-off frequencies, high return loss, and excellent linearity. Extensive study shows that proper selection of fabrication techniques and type of material optimizes the performance of microstrip filter design, thereby increasing its practicability for emerging wireless communication systems.
本文介绍了用于微带带通超宽带(UWB)滤波器设计的优化技术。讨论了基于各种缺陷接地结构技术、谐振器设计和介电材料类型的优化。在无线通信系统中,实现在超宽带频段的微带带通滤波器具有控制通带和阻带频率响应的关键特性。研究了优化技术以实现带通微带滤波器的最佳性能,以确保最小的插入损耗、高选择性、紧凑性、截止频率的急剧过渡、高回波损耗和良好的线性。广泛的研究表明,适当选择制造技术和材料类型可以优化微带滤波器设计的性能,从而提高其在新兴无线通信系统中的实用性。
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引用次数: 1
Performance-Shaping Factors of Personnel Performing Evacuation and Escape on Offshore Installations in Tropical 热带地区海上设施人员疏散和逃生的性能塑造因素
Pub Date : 2020-09-01 DOI: 10.7454/mst.v24i2.3756
N. Norazahar, Nur Azizah Arryanie Morshidi, A. Ahmad, Wijayanuddin Mohd Ali
Performance-shaping factors (PSFs) are used to address the strengths and weaknesses of workers performing escape and evacuation activities. These PSFs are time, environmental factors as stressors, complexity of activities, experiences and training, interaction between workers and emergency equipment, workers’ physical conditions, and procedures. This paper presents a survey work on fitness for the duty of workers performing basic offshore survival and emergency response training. The training provides credible scenarios of escape and evacuation in case of an emergency of offshore installations in tropical waters. The survey is conducted among participants of the tropical basic offshore safety induction & emergency training with emergency breathing system. Sixteen participants of the training voluntarily answered the set of questionnaires. The survey work addresses the fitness for duty among workers performing escape and evacuation on offshore installations. Survey results indicate that workers must have good physical conditions and mental fitness in order to accomplish the escape and evacuation activities.
绩效塑造因素(psf)用于解决工人执行逃生和疏散活动的优势和劣势。这些psf包括时间、作为压力源的环境因素、活动的复杂性、经验和培训、工人与应急设备之间的相互作用、工人的身体状况和程序。本文介绍了一项关于近海基本生存和应急训练人员值班适能的调查工作。培训提供了在热带水域海上设施发生紧急情况时可信的逃生和疏散情景。本调查是在热带基础海上安全诱导及紧急呼吸系统应急培训的参与者中进行的。16名培训参与者自愿回答了这组问卷。调查工作涉及在海上设施上执行逃生和疏散的工人的职责适应性。调查结果表明,工人必须有良好的身体状况和心理素质,才能完成逃生和疏散活动。
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引用次数: 0
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Theory of Computing Systems \/ Mathematical Systems Theory
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