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Excessive use of fertilizers in agriculture to sustain the food needs for rapid demographic growth has been reflected in serious negative consequences on the aquatic environment, through eutrophication which has become a global problem. Besides creating a hypoxic environment for fish and other aquatic species, as well as navigation difficulties, clogging electromechanical equipment at hydropower plants (HPPs) is another major problem caused by aquatic biomass bloom in fresh-water streams and coastal sea water as a result of the agricultural nutrient-rich runoff. This paper aims to present some issues related to reducing the operating efficiency of the electromechanical equipment, especially turbines, hydro-generators and hydraulic steel structures which are vulnerable to clogging by algal biomass and aquatic weeds grown along the rivers or in sea waters. An efficient and sustainable method of harnessing the energy potential of the aquatic biomass collected from the water storage lakes at the dams of hydropower plants but also from the coastal areas is presented as well. Apart from the direct benefits that harnessing aquatic biomass may bring to produce renewable biogas, this sustainable practice can avoid inefficiency or malfunctions of the hydropower plants caused by clogging hydro-equipment and components.

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Keeping track of the progress on software projects can be difficult and time consuming. Progress tracking requires developers to track progress by hand or digitally neither of which have good support for collaborative team processes. In this paper we present DashVis a tool to help support teams to track progress more effectively using large touch displays and visualization techniques. We conducted a study and found the visualizations to be very effective in supporting teams to gain a more accurate way of keeping track of progress. With large touch displays becoming ubiquitous in the work place and the demand for software teams to understand their progress more effectively there is a need for tools like DashVis.

This study assessed the suitability of incorporating waste transfer stations in six developed future municipal solid waste (MSW) management options for urban environments within and surrounding Harare city. MSW collection and transportation is a major challenge characterising the management of MSW being generated, currently consuming over 70% of the MSW management budget. Life cycle assessment showed increased contribution of waste collection and transportation to acidification, eutrophication, global warming and human health impacts of 0.012 species.year, 0.0002 species.year, 0.065 species.year and 34 DALYs respectively for all the developed MSW management options. The greatest impact in regards to species extinction rate (species.year) is witnessed under global warming due to the emission of greenhouse gases from the burning of fuels during MSW collection and transportation. These and other factors such as land unavailability to construct MSW management facilities (landfills, waste to energy and material recovery) and human health hazards associated with these facilities near population centres justify the incorporation of waste transfer stations in future MSW management options. This study further recommends the need for legislative and regulatory framework for proper siting, design and operation of transfer stations to enhance their effectiveness and efficiency and reduce their impacts to the community and environment.

Solid waste generation, including waste tyres, has become a global challenge in many developed and developing countries. South Africa is seen as a growing and emerging country that is also contributing to the accumulation of waste tyres. This led to the government pronouncing its intentions to ban the landfilling of all waste tyre assortments throughout the country as they pose serious health and environmental risks. The Recycling and Economic Development Initiative of South Africa (REDISA) implemented its Integrated Industry Waste Tyre Management Plan (IIWTMP) in 2015 with the aim of redirecting waste tyres away from landfill sites and create green jobs from the recycling thereof. However, from initiation the Plan drew criticism from various organisations plus its improper corporate governance, unwillingness to adhere to National Environmental Management (NEM) Amendment Law Bill, deviations from the original Plan, and as well as operational and performance non compliances were some of the reasons cited for the liquidation. This paper, a desktop literature study focuses on the successes and failure of the REDISA Plan.

The need for efficient solid waste management practices has become more pressing, especially in developing nations largely experiencing a population boom in urban areas. Currently, however, it is only developed nations that have embraced resource efficient practices and technologies to produce energy, heat, fuels and compost from solid waste. This paper reviews such global trends and best practices as a benchmark against current practices within the context of Botswana. It also reviews the opportunities for Waste to Energy (WtE) in this developing nation by taking a solid waste inventory. A literature survey revealed that Botswana is still operating in the previous policy direction of keeping the society clean to avoid the hygienic effects of waste. The collection and disposal of waste is partly decentralized with several private players. There is little recycling within the country; most private companies collect recyclables and send them to South Africa. Anaerobic digestion and incineration are the only WtE opportunities that had been previously identified with no major commitment on implementation. There are alternative WtE technologies, therefore the economic and technical requirements should be weighed against the corresponding capacity of the nation.

Garbage collection (GC) is ubiquitously used to reclaim useful space during the data update process in NAND flash memories. Conventional GC algorithms keep track of a table storing the number of valid pages in each block and select ones with the smallest number of valid pages to erase. We notice that NAND flash not only stores user data but also keeps updating meta data frequently and one of the most important requirements of GC for meta data updates is latency predictability, which means the latency of GC should not only be low on average and on tail distributions, but also independent of workload, i.e., the sequence of meta data updates. It is also desirable to have all NAND pages/blocks written the same number of times to avoid any latency incurred by wear leveling. In this paper, we propose GC algorithms that do not require any look-up tables, which avoids the latency for reading the table and sorting the number of valid pages, and intrinsically enables all pages to be worn equally. Several GC algorithms are proposed to make trade-offs between over-provisioning and write amplification. We also provide sufficient and necessary conditions that the proposed GC algorithms will not encounter a deadlock, i.e., the algorithms can run continuously on all meta data update sequences without data loss.

International audience; Internet connected devices are becoming increasingly common in consumer homes. These devices combined with software entities are used to build Internet of Things (IoT) applications. As democratization of IoT takes shape, developing reliable IoT applications remains a challenge for consumers because these applications exhibit characteristics such as distribution, dynamicity, and heterogeneity, which make their design, development and maintenance difficult. In this paper, we use formal methods to ensure correct composition of objects and propose a reliable deployment mechanism in the context of an IoT application. Objects are modelled using an interface description model integrating a behavioural specification of the object functionality. We provide formal validation techniques for verifying that the composition is correct. A deployment plan is generated for automating the instantiation of all objects involved in a valid composition. All the proposals have been implemented as a prototype tool and experiments were carried out for evaluating the tool performance and usability.

Designing and deploying a safe and reliable wireless sensor network involves deep knowledge of the propagation environment, as the performance can be compromised by unknown or unpredictable factors like interference, vegetation, terrain or excessive humidity. An accurate propagation model is essential for developing a cost-effective wireless sensor network, however, a guide that will allow the frequency selection based on some input data that can be considered as default constraints for any RF planner (e.g. distance between sensors, lack of electricity, minimum throughput, etc.) can always serve as an alternative to rather expensive RF propagation studies.

Next generation non-volatile memories, like Resistive RAM, Spin-Transfer Torque Magnetic RAM and Phase Change Memory, are byte- addressable with very low latency, bridging the large performance gap between DRAM memory and NAND flash storage. For this reason we think of them as Storage Class Memories (SCMs), meaning their main use could ideally be as main memory but the non-volatility and high density could also fill some of the needs for durable storage. The path to using SCMs as main memory will necessitate significant changes to prevailing CPU architectures, so at first our focus was on enabling their early market adoption as ultrafast storage in commodity systems. In stark contrast to NAND flash, whose read latency of a tenth of a millisecond dominates the total system response latency to a storage request, SCM-based devices are so fast that attach interface and host device driver latencies, which are in the microsecond domain, start to dominate the total response latency, hindering greatly the performance of SCMs in commodity systems. Moreover, the latency jitter introduced by host hardware and software and by controller firmware further affects the Quality of Service (QoS) of solid-state drives based on SCMs. In this paper we discuss various factors that degrade the QoS, including host software and machine configurations. A particular fine- tuning of an x86 host machine, a well-designed device driver and a low latency device controller result in an ultra-low latency system with excellent QoS. We measure less than 4 μs latency for 99.999% of I/O requests at queue depth one, and less than 7 μs at queue depth 32, from an SCM-based block device on PCI Express interface.

Following the implementation of the antigalloping devices for the 400 kV o/h lines with 2 subconductors per phase, as explained in our paper presented by the occasion of the ICOLIM 2014 in Budapest, a new antigalloping device of the same torsional damper and detuner pendulum type was created and already implemented on some of the 400 kV with 3 subconductors per phase in Romania, in 2015. The device is characterized by combining the properties of torsional damping with those of detuning, avoiding the energy transfer from the torsion to the vertical motion. The torsional damping leads to a higher critical wind speed at which the galloping instability appears and limits its amplitude, while the detuning characteristic of the device separates the torsional and vertical frequencies. The new device design took the main shape of that used for 2 conductors per phase, the rigid spacers being now triangular and some differences in the dimensions having to be considered. Nine alternatives were taken into account for testing. Finally, based on the transfer function diagrams, two alternatives were further developed and manufactured, the Light (L) and the Heavy(H). The axonometric drawing and the view one are shown in the figure. The difference between these two consists of different counterweights (H-10.9 Kg and L-8.9 Kg) and different distance between the counterweight axis (H-860 mm, respective L-830 mm). The concept of the damping pendulum as torsional damper and detuner (TDD) was created and reported in 1993 by its authors led by Prof. Jean-Louis Lilien from University of Liege-Belgium. Several versions were designed, tested and even used in some minor projects, demonstrating their high capacity to solve the risk of the overhead line conductor galloping with usual frequencies in the range 0.4–0.6 Hz. The parameter describing the damping performance is the transfer function with values in the range 1.5–2.5 in the case of the previous versions. The new version transfer functions came to much better values. A description of the pendulum parts, tests carried out and the final design are presented. The pendulum can be easy mounted in live-line conditions.

The paper aims to study which type of orifice type (round or square) is more efficient for an induction motor fan cowl, in order to obtain an increased air flow rate. The analysis begins from an already existing fan cowl (with square orifices) and it is shown that it is possible to improve the air flow rate. The chosen efficiency parameter is the flow coefficient, which is calculated using computational fluid dynamics means.

The concept of the damping pendulum as torsional damper and detuner (TDD) was created and reported in 1993 by its authors led by Prof. Jean-Louis Lilien from University of Liege-Belgium. Several versions were designed, tested and even used in some minor projects, demonstrating their high capacity to solve the risk of the overhead line conductor galloping with usual frequencies in the range 0.4–0.6 Hz. The parameter describing the damping performance is the transfer function with values in the range 1.5–2.5 in the case of the previous versions. The new version transfer function came to 3.0, the best met value till now. A description of the pendulum parts, tests carried out and the final design are presented. The pendulum can be easy mounted in live-line conditions.

Distributed storage systems use erasure codes to reliably store data with a small storage overhead. To further improve system performance, some novel erasure codes introduce new features such as the regenerating property or symbol locality, enabling these codes to have optimal repair times and optimal degraded read performance. Unfortunately, the introduction of these new features often exacerbates the performance of other system metrics such as encoding throughput, data reliability, and storage overhead, among others. In this paper we describe the intricate relationships between erasure code properties and system-level performance metrics, showing the different tradeoffs distributed storage designers need to face. We also present Spider Codes, a new erasure code achieving a practical trade-off between the different system-level performance metrics.

This paper discusses a practical implementation for photogrammetry missions in an UAV setting. Further advances, which exploit geometrical properties of the problem are considered. In particular, a bi-level optimization procedure which minimizes the total path-length is discussed. Various constraints and limitations are taken into account.

Flash memories use the amount of charge (e.g., electrons) trapped in floating gate transistors to represent data. Charge leakage will cause data retention problem by unidirectionally shifting the cell-level distribution. Balanced codes are an effective means to adjust read thresholds adaptively and tolerate the charge leakage under unknown retention environments. For multi-level cell (MLC) flash memories with 4 levels, 2 binary logical pages are mapped to one quaternary physical page. In order to achieve a small read latency, one (or two, respectively) read threshold(s) is (are) applied to the physical page to retrieve data for the least significant bits (LSBs) (or most significant bits (MSBs), respectively). In this paper, we propose two coding schemes that use balanced codes for multi-level flash memories, which tolerate charge leakage and provide fast page read simultaneously. We prove that our coding schemes asymptotically bring no rate penalty (2 bits/cell for quaternary cells). We establish a model of the programming, retention, and read for MLC, then theoretically calculate the raw bit-error-rate (RBER) and page-error-rate (PER), and compare the performance of read threshold adjustments based on balanced codes and the conventional scheme that estimates the cell level drift. It is shown that for a fixed PER, the requirement for error correction codes (ECCs) when using balanced codes is much less than that of using conventional schemes, which has the benefits of ECC rates, decoding delay, and decoding complexity.

The emergence of unmanned aerial vehicles for large scale monitoring of ground infrastructure has challenged new designs for electronic sensor systems capable of timely, accurate and compntationally effective measurements. A conventional design issue is balancing the complexity of the sensing subsystem with advanced data processing algorithms in order to obtain quality information regarding the airplane's posture and orientation. The paper presents the generic architecture of the navigation sensing system for a fixed-wing mini-UAV, at both the physical and algorithm levels. The focus is set on a sub-problem, namely altitude estimation by sensor fusion using barometric pressure and GPS data. Results are discussed based on actual flight log data and the approach is extended towards speed estimation: air, ground and wind influence. Conclusions are drawn regarding efficient implementation of the method in relation to the onboard embedded processing capabilities.

The design of the payload for a UAVs robotic assembly system is of the highest importance. This is the piece of the work cell that physically interacts with the environment. The paper present a payload for HIRRUS V1, which is analyzed in terms of kinematic and dynamic. Functional calculation is presenting for the payload mechanism. Also, dynamic modeling are presented for retracted payload and small doors sliding, for different simulations.

Data describing biomaterials have a complex structure because they describe the so static characteristics and dynamic characteristics. These data also include time interaction with other organic or inorganic materials. Due to their large variety looking for a particular biomaterial it is difficult due to the complexity of their representation. A representation of biomaterials by using the techniques of expert systems can help identify a particular biomaterial. By developing methods and analysis techniques for biomaterials increases measurement accuracy. Following their reconsideration they can not meet their purpose intitial medical device. This paper aims to outline the architecture of an expert system that manages a database of biomaterials.

The concept of the damping pendulum as torsional damper and detuner (TDD) was created and reported in 1993 by its authors led by Prof. Jean-Louis Lilien from University of Liege- Belgium.

This paper presents a tool used to audit the cloud adoption within a company. The first section states the main advantages of the cloud computing environment together with its biggest challenges that can introduce significant risks within a company. In order to assess properly the cloud computing adoption, we developed a web based tool that assists the internal auditor in the pre-migration process. Section II describes in details the Migration Assessment Tool (MAT). Starting with its architecture, we presented the main objects manipulated by our application in order to implement a cloud adoption assessment. In order to compute the impact, we classified the questions in different domains and we defined the dependencies between the questions. At the end of section II, we presented the process implemented in MAT when assessing a cloud migration. The paper ends with conclusions that state the main benefits of our approach and future improvements for MAT.

Agile methods are widely adopted in software development. They are based on agile principles that sharply contrast to traditional command-and-control management methods. Such methods emphasize the importance of highly interactive self-organizing teams and close collaboration of all stakeholders, as well as values like courage, openness and respect. However, recent studies show that graduates and undergraduates of computer science often lack the collaborative and communicative skills necessary for agile methods and, thus, are not yet well enough educated for agile development approaches. Therefore, new approaches or more adequate educational methods for teaching the necessary communication and collaboration skills need to be developed. In a recent interview study, the authors elicited specific collaboration and communication skills needed in agile teams. In this paper, we present results from this study and discuss teaching concepts for collaboration skills from both engineering and psychological points of view. We suggest an approach on how to integrate these concepts into university courses, that focuses on active learning of agile collaboration. We have started implementing the proposed concept in a software engineering course and report on the experiences we have made and on the challenges that we have encountered.

This paper presents the main challenges in a cloud computing architecture relate to the security of the provided services. In the introduction section are described the factors that prove the cloud computing necessity in the actual IT context. In order to achieve all these benefits, the enterprises experience stated an approach that ensures a smooth migration with optimal results. The first section ends with a synthesized process that explains the main steps that must be performed to move from traditional architecture to cloud computing services. When moving to on-demand services, the consumer can choose one of the available “flavors” of cloud computing services - these are described in Section 2. Despite all obvious advantages and benefits, there are also security challenges in cloud computing architecture structured by Cloud Security Alliance in [1]. The main security domains are mentioned in the third section while the forth section describes our approach that addresses the challenges in the communication between the on-premise and on-demand services.

To calculate the accurate value of the dynamic capacitance of a line under corona surge is very important taking into account that the dynamic capacitance value is influencing strongly the distortion of the surges travelling on a line toward the substations. So, it is possible to know the most probable shape and amplitude of the surge in any point of the line to allow the designers to take into account the most adequate measures of protection. Also, in the case of the induced overvoltage surges the dynamic capacitance has a major function, the induced overvoltages just in the initiating point being distorted because of the corona discharge and so easier protection measures having to be taken in the medium voltage distribution lines and substations as well.