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Wireless Sensor Network System for Hydrological Monitoring

Wireless Sensor

Hydrological monitoring and real-time access to Wireless Sensor data are valuable for hydrological research and water resources management. In the recent decades, Wireless Sensor rapid developments in digital technology, micro-electromechanical systems, low power micro-sensing technologies and improved industrial manufacturing processes have resulted in retrieving real-time data through Wireless Sensor Networks (WSNs) systems. In this study, a remotely operated low-cost and robust WSN system was developed to monitor and collect real-time hydrologic data from a small agricultural watershed in harsh weather conditions and upland rolling topography of Southern Ontario, Canada. The WSN system was assembled using off-the-shelf hardware components, and an open source operating system was used to minimize the cost. The developed system was rigorously tested in the laboratory and the field and found to be accurate and reliable for monitoring climatic and hydrologic parameters. The soil moisture and runoff data for 7 springs, 19 summer, and 19 fall season rainfall events over the period of more than two years were successfully collected in a small experimental agricultural watershed situated near Elora, Ontario, Canada. The developed WSN system can be readily extended for the purpose of most hydrological monitoring applications, although it was explicitly tailored for a project focused on mapping the Variable Source Areas (VSAs) in a small agricultural watershed.

Long-term, high-quality climatic and hydrological data are essential for hydrological research and the implementation of effective water management strategies at both field and watershed scale. Monitoring and collecting long-term data from remotely located watersheds are time-consuming and expensive; due to the need for frequent visits to the sites for maintaining and monitoring the instruments and for data collection [1]. Though this approach involves a significant amount of time and resources; it is imperative and valuable. Currently, a number of data acquisition technologies are being used to obtain hydrological data. Accuracy, resolution, and scalability are some of the significant issues that need to be addressed in developing an efficient and robust hydrological monitoring system [2] [3]. In the earlier techniques, analog type network with cables and a number of sensors wired to data loggers were used for hydrological monitoring. The need for cabling in the field increases costs and restricts the spatial size of the monitoring area [4] [5] , whereas the digital wireless networks can be deployed to collect long-term data at larger scale and resolution while maintaining robust and reliable network performance [6] [7] [8].

In recent years, the rapid development of WSN technology has created new opportunities for sensing, computing, and communication in a wide range of applications in the field of science and engineering. WSNs integrate real-time sensing, computing, and communicating processes and provide an efficient and cost-effective observation technique, monitoring, gathering data, performing local computations and relaying the aggregated data capabilities [9] [10].

WSNs comprise of few to several “nodes” (known as a Mote in North America) where each node is connected to one or more sensors [11]. Each sensor node has four key components: 1) the microprocessor & ADC (analog to digital converter), 2) transceiver & antenna, 3) memory unit, and 4) external sensors [12]. The individual sensor node consists of a number of hard-wired sensors. Each node is wirelessly connected to other nodes, and finally to a central base station (Figure 1). A digital WSNs comprised of spatially distributed nodes connected to sensors communicates bi-directionally to the central location [13]. As WSN does not require cables, they are cheaper and easier to install, in addition to requiring low maintenance. Flexibility, easy and rapid deployment, self-organization, high sensing reliability, and low-cost characteristics of WSNs make them a promising technology for various applications [14] [15].

WSNs can be used with many diverse types of sensors, such as thermal, optical, acoustic, seismic, magnetic, infrared, pressure and radar [16]. Sensors used in WSNs convert physical parameters like temperature, soil moisture, pressure, light, speeds, etc. into a signal and measure them electrically [17].

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Design/Planning for Sustainable Development

Sustainable Development

Human society locally and globally needs to better Sustainable Development understand and respond to ever-more complex, interwoven problems: environmental degradation; climate instability; persistent poverty; disparities in Sustainable Development human health; growing income/wealth inequality; economies and infrastructures vulnerable to climate shock; and mounting socio-political unrest. Cities are where most people live, urbanization is a strong upward global trend, and cities bring all these problems into sharp, compelling focus. Since outcomes stem from processes and systems, we argue transformative changes depend on re-imagining the Urban Design, Urban Planning and Urban Development Practice (UD/UP/UDP) process. While there has been insufficient attention to process innovation— with technological aspects tending to dominate UD/UP/UDP work—emerging systems views of cities, and disenchantment with existing modes are enabling. We propose an empirically based integrative frame to tackle recognized conundrums, and inform an adaptive UD/UP/UDP process—from concept through design, assessment, planning, implementation, project functioning and monitoring. The frame contemplates six domains (6-D): 1) Project ethos, concept, and framing; 2) sectors, topics, and issues; 3) Varying spatial and temporal scales; 4) Stakeholder interests, relationships and capacities; 5) Knowledge types, modes and methods; and 6) Socio-technical capacities and networks. The frame, process and outcomes constitute a socio-technical enterprise (STE) approach to UD/UP/UDP work, with implications for education, training, and professional practice. We highlight the pivotal role Integrators and Universities play, and the scalability of STE knowledge/capacity networks. The case of Greater Mexico City/Central Mexico Urban Region illustrates the utility of the approach in a hyper-complex, climate-change vulnerable regional context.

In 2007, the world passed a singular threshold: for the first time in human history more people lived in urban areas than rural ones [1] ―and the trend has continued strongly in an upward direction. In the aggregate most of this growth is happening in “mid-sized cities” in the so-called “developing world” [1] , although very large cities―mega cities (>10 million inhabitants) and very large urban agglomerations like Cairo, Tokyo, Los Angeles and Mexico City―continue to present the most serious challenges to social, economic and environmental sustainability, while testing the viability of traditional approaches to urban design and providing strong incentives to innovate. Among the signs most cities are moving away from sustainability are indicators of declines and inequities in social justice, economic justice and environmental justice, and those related to weak climate-change resilience. In 2014, the 5th IPCC Assessment Report (AR5) stated: “Climate change is a threat to sustainable development. Nonetheless, there are many opportunities to link mitigation, adaptation and the pursuit of other societal objectives through integrated responses. Successful implementation relies on relevant tools, suitable governance structures and enhanced capacity to respond” ( [2] , p. 94).

Almost 30 years after “Our Common Future” first presented the sustainable development paradigm to the world [3] , 2016 saw a critical review of societal progress―and lack thereof―with the United Nations publication of “Sustainable Development in the 21st Century” (SD21 Project) [4] . It states: “[A] new political deal is needed, which provides a clear vision and way forward for the international community, national governments, the private sector, civil society and other stakeholders for advancing the sustainable development agenda in an integrated manner” ( [4] , p. iii). These high-level multi-lateral perspectives are themselves inescapably political, but they do endorse an integrative approach and the need for public agencies and civil society groups to engage constructively with each other. However, they fail to call out critical foundational conceptual and practical difficulties, conundrums and gaps in societal capacity that undermine success (see discussion of Millennium Village Project in [5] [6] ).

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Polymer Modified Concrete of Blended Cement

Blended Cement

This paper deals with the effect of blended cement and natural latex copolymer to static and dynamic properties of polymer modified concrete. The polymer was used copolymer of natural latex methacrylate (KOLAM) and copolymer of natural latex styrene (KOLAS) with composition of 1%, 5%, and 10% w/w of weight of blended cement in concrete mixture. They are tested for compressive strength, flexural strength, splitting tensile strength, and modulus elasticity for static analysis, and impact load and energy dissipation profile for dynamic analysis. The result shows that KOLAM with concentration 1% give better performance in static and dynamic properties. The KOLAM 1% gives improvement in flexural strength, splitting tensile strength and modulus elasticity about 4%, 13% and 3% compared to normal concrete. And for dynamic properties, KOLAM 1% could reduce impact load up to 35% and improve energy dissipation capacity about 45% compared to normal concrete. The concentration of KOLAM higher than 1% resulting negative effect to static and dynamic properties, except modulus of elasticity. For KOLAS, there were no positive trends of static and dynamic properties.

Concrete had been used in many decades due to its properties and economics. However, it has some limitations such as low failure strain, low flexural and tensile strength, low chemical resistance, and etc. There are many solutions for eliminating its limitation. The most common in construction is using steel reinforcement for improving flexural and tensile strength [1] . Research had been done by using titanium alloy for steel reinforcement system in aiming of earthquake resistant building [2] . The other solution was high performance concrete application [3] . The high performance concrete is produced by low water/cement ratio, adding admixture, additive and etc. So, high performance concrete will need more cement and costly. Also high performance concrete will be brittle, and more susceptible for cracking [4] .

The polymer addition into concrete mixture could be used for eliminating concrete limitation. The polymers in concrete have been used in many decades for widen the concrete applications. The polymer in concrete could be functioned as binder either with or without cement in form of polymer modified concrete, polymer concrete or polymer reinforcement concrete, or filler. Polymer as binder would improve the interfacial zone, and polymer as filler would fill the void. So it would result low porosity concrete [5] . The polymers for concrete additives are varied, such as elastomer (natural rubber, synthetic rubber), thermoplastic (PVA, styrene-acrylic, etc.), thermoset (epoxy), bituminous (tar, asphalt) and latex modification [6] . And they have been researched for many concrete applications.

The Natural rubber had been researched for improving the concrete strength [7] and durability in extreme environment [8] . For synthetic rubber, the most used in construction is Styrene Butadiene Rubber. Researches had been done by interacting SBR with silica fume for modifying of interfacial zone [9] , its effect in concrete into microstructure and chloride permeability [10] and its effect as admixture in high performance concrete [11] . The other polymer used in construction is epoxy. Research of epoxy had been done for improving concrete durability [12] , its effect to microstructure [13] and fire resistant [14] .

The polymer addition into concrete mixture could be used for improving the earthquake resistant and damping capacity. The styrene Butadiene Rubber (SBR) had been research for that purpose by evaluating of energy dissipation of concrete [15] . Also, rubber in form of crumb rubber had been research for improving the energy dissipation [16] and static and dynamic properties [17] .

Indonesia is second largest producer natural rubber in the world. The rubber is exported as natural rubber, about 80% [18] . In order to get added value of rubber, research have been done of modification of natural rubber (latex form) into copolymer [19] . The modified latex had been research for improving strength and durability of concrete [20] , its effect into fire resistant properties [21] and earthquake resistance [22] . The Researches of copolymer of natural latex modified concrete used ordinary Portland cement as binder.

There is a new trend of Indonesian cement industry, by reducing the production of ordinary Portland cement and more production volume in blended cement production, as a commitment to Kyoto protocol for CO2 reducing. So, this research was developed by replacing the Ordinary Portland cement into blended cement in producing polymer modified concrete. The blended cement was composing of min 65% clinker and max 35% supplementary cementitious materials such as fly ash, trass/natural pozzolan, and lime. The supplementary cementitious materials have been used for improving concrete durability by forming additional CSH [23] and producing sustainable concrete. The use of supplementary cementitious materials could reduce the CO2 emission and to be environmental friendly in cement production [24] .

Besides using blended cement, this research was dealing with modified natural latex as concrete additives. The polymers are copolymer of natural latex methacrylate (KOLAM) and copolymer of natural latex styrene (KOLAS). The polymer modified concrete of blended cement and copolymer of natural latex were evaluated for static and dynamic analysis. The static properties are compressive strength, flexural strength, splitting tensile strength and modulus of elasticity. The static properties were evaluates as a base of concrete strength evaluation. Based on the static properties, research was developed into dynamic evaluation. The dynamic evaluation was done based on impact load and energy dissipation profiles. The dynamic evaluation will be used as a preliminary research for concrete with impacting resistant (good damping capacity) and earthquake resistant application. So, by polymer addition will widen concrete application.

The involved blended cement and copolymer of natural latex could be used as an alternative for improving concrete performance in more sustainable. Due to blended cement more sustainable than ordinary Portland cement and copolymer of natural latex is renewable material. Thus, the research could be used as a reference in green construction for designing of impact and earthquake resistant building.

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Stabilization with Binders and Sands

Binders and Sands

The present study aims at helping to search for preventive solutions to pathologies of constructions in Togblécopé in Binders and Sands Togo, by the reduction in the withdrawal and swelling of foundation grounds through their stabilization. Togblécopé’s clay Binders and Sands taken from 1 m, 2 m and 3 m deep, and mixed with four binding materials (cement, sea sand, silty sand and lime). Tests of identification and free swelling with odometer are carried out on pure and stabilized materials. What emerges from these tests is that the limits of liquidity and plasticity are rising along with the rate of stabilizers while the index of plasticity is falling. Cement and lime cause a reduction in the index value of plasticity by almost 50%. The more the sand’s grain size, the more the reduction in the plasticity index. The swelling potential is reduced by 60% for cement and lime, 30% for sea sand and 20% for silty sand. The present study is a contribution to the reduction in deflations from 20% to 60% of some parts of constructions in order to limit cracks.

Civil engineering works aim at soils called foundation soil that is mostly clayey soils. Some clays present swelling or retracting features. Construction on such a clayey soil requires a thorough campaign of research, identification and characterization of its swelling potential. Swelling soils are very fine soils whose components are made up of layers. The swelling feature is a very complex issue, since it is the outcome of several associated phenomena that cannot be separated in terms of experiment for identification of each mechanism effect [1] . In dry season, swelling soils lose their saturation and the quantity of water falls down. They undergo a relatively significant reduction in volume; conversely, when they become hydrated again, the water goes through cracks and tends to capture its initial volume. Such swelling of clays depends on the state of soil capacity and on hydric conditions. The presence of swelling soils poses then a great deal of problems for designers of works [2] . A large number of works, constructed on marneous formations, show very often signs of degradations. These latter, characterized by cracks at the superstructure, are due to the phenomenon of withdrawal which has not been considered during their implementation and which are getting worse in the dry season. Moreover, the resulted deformations are not uniform following all directions because of the anisotropic structure of the material and depend mainly on the state of applied constraint.

Therefore, the treatment of soils is often used to upgrade their resistance in order to reduce or to increase their permeability and also to lower their compressibility [2] [3] . It is also used to reduce the soil sensitiveness to variations of the water content as is the case with expansive soils [4] [5] .

In Togo, or more exactly in Togblécopé, living quarters and other constructions go through sweeping degradations (Figure 1). We have been experiencing for many decades an instability characterized by a state of construction with widespread subsidence and cracking in different parts of constructions. The causes of such degradations can be searched in the instability of soil that is swelling and then subject to bad weather. This work aims to help search for preventive solution to deformations of constructions in Togblécopé in Togo through the study of swelling soils in the region. Additional lime, cement, sea sand and silty sand are used to help reduce instability of the soil by reduction in its withdrawal and swelling.

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Circle Which May Represent the Loading of the Dual Wheels

Dual Wheels

This work aims to look for a simplifying surface that can represent the effect of the dual wheels on the variation of the stress and deformation state prevailing during the passage of traffic loads. This was facilitated by the results of Thiam (2016) [4] obtained on the distribution of the vertical contact stress in the space described by the dual wheels. The analysis of the results of this study, on all the loading circles considered, shows that the radius loading circle equal to 0.181 m makes it possible to most probably represent the effect of the dual wheels. With this new surface, the effect of the dual wheels can be determined in 2D. The choice of this load is confirmed by a study in case of overload. Thus, the single axle with dual wheels is represented by a simplified diagram equipped on each side by a disk of radius 0.181 m. These results are obtained using a numerical simulation under Cast3M with a gravelly lateritic pavement.

The concept of equivalent single-wheel load has long been used in the structural design of the pavement. In order to design the exchange of these loads at the equivalent single wheel load (ESWL), calculation methods have been proposed by some authors like [1] and [2] . These methods are particular adapted to the design of airport pavements. The rapidly changing configuration of heavy trucks, equipped with multiple wheels, has highlighted the need for a pavement design method, according to which multi-wheel loading can be linked to a common standard independent of the configuration of the road wheel. In many cases, the loading of the dual wheels is described by two circles with a radius of 0.125 m and a center distance of 0.375 m. The configuration of this load (2 disks spaced) does not allow to model the whole structure-loading in 2D [3] . The simplification of this loading into an equivalent single load; provides pavement designers with a practical means of analysis and to evaluate the state of stress and deformation at the level of the roadway. The load circles are converted to a surface equivalent to a single loading circle so that the design criteria based on the single-wheel loading circle can still be applied. This will allow us to have the effect of dual wheels in 2D with the new radius. Although further research is needed in this direction, the simplification method presented here will provide a satisfactory solution to the problem of loading wheels coupled to a loading circle. The studies conducted as part of this work are essentially based on a numerical simulation using the Cast3M finite element calculation code.

The study of the distribution of the vertical contact stress in 3D space by [4] has a particular advantage for the realization of this research. This distribution is performed with the loading of the dual wheels described by 2 disks with a radius of 0.125 m and a distance of 0.375 m and that of a wheel simple radius 0.125 m on lateritic pavements. The results of his studies show that the vertical contact stress is non-uniform on the circular footprint and has a significant influence on the deformation of the pavement at the level of the bituminous layer. This deformation is maximum in the center of the circular imprint where the vertical stress is maximum. The distribution of the vertical contact stress does not influence the platform [4] . This non-uniformity has been shown by [5] under a pneumatic tire thanks to the VRSPTA system (Vehicle-Road Surface Pressure Transducer Array) according to the intensity of the load and the inflation pressure. These results show that it is possible to determine non-uniform distributions of the vertical contact stress for modeling to evaluate their effect. In other words, the results obtained with the semi-axle with dual wheels are of particular interest for the size of roadways. The stresses induced in the structure by the load are maximum in the center of each circular imprint but not in the center of gravity of the half-axle (or plumb the twinning) [4] . The implementation of these previous results allows us to approach the notion of an equivalent surface.

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