Study of the Impact of Grid Disconnections on the Production of a Photovoltaic Solar Power Plant: Case of Diamniadio Power Plant

Today, renewable energy projects connected to the interconnected network, with powers of the order of tens of megawatts, are more and more numerous in sub-Saharan Africa. And financing these investments requires a reliable amortization schedule. In the context of photovoltaic systems connected to the interconnected electricity grid, the quintessence of damping is the amount of energy injected into the grid. Thus it is fundamental to know the parameters of this network and their variation. This paper presents an evaluation of the impact of power grid disturbances on the performance of a solar PV plant under real conditions. The CICAD photovoltaic solar plant, connected to the Senelec distribution network, with an installed capacity of 2 MWp is the study setting. An energy audit of the plant is carried out. Then the percentage of each loss is determined: voltage drops, module degradation, inverter efficiency. The duration of each disconnection is measured and recorded daily. The corresponding quantity of lost energy is thus calculated from meteorological data (irradiation, temperature, wind speed, illumination) recorded by the measurement unit in one-minute steps. The observation period is three months. The total duration of disconnections related to the instability of the electrical network during the study period is 46.7 hours. The amount of energy lost is estimated at 22.6 MWh. This represents 2.4% of the actual calculated production.

Study of the Thermodynamic Properties of Thermal Plasmas of Fluoroalkylamine-Air Mixtures

Knowledge of thermodynamic properties as well as parameters such as energy density and power flow isimportant for modeling thermal plasmas of fluoroalkylamine-air mixtures. In this paper, these thermodynamic properties of fluoroalkylamine-air mixture plasmas are calculated in a temperature range of 500 K to 20,000 K at atmospheric pressure and local thermodynamic equilibrium (LTE). The Gibbs free energy minimization method is used to determine the chemical equilibrium compositions of the plasmas that are needed to calculate the thermodynamic properties. These thermodynamic properties are then used to calculate the energy density and power flow of these plasmas. The variation of the energy density is related to the variations of the density and mass enthalpy. We notice that, this energy density increases with the percentage of air in the mixture for temperatures higher than 7000 K. The power flow, which depends also on density, enthalpy mass and sound speed, increases with the percentage of air in the same temperature range. Energy density and power flow results show that increasing air percentage in the mixture can be more interesting for damaging gaseous chemical species such as CF2, CO, HCN, and HF appearing at low temperatures with high concentrations.

PREPARING NANO-CRYSTALLINE La DOPED WC/Co POWDER BY HIGH ENERGY BALL MILLING

The La doped WC/Co powder was prepared by high energy ball milling. The changes of crystal structure, micrograph and defect of the powder were investigated by means of XRD (X-ray diffraction), SEM (scanning electron microscope) and DTA (differential thermal analysis). The results show that adding trace La element into carbides is effective to minish the grain size of WC/Co powder. The La doped carbides powder with grain size of 30nm can be obtained after 10h ball milling. The XRD peak of Co phase disappeared after 20h ball milling, which indicated solid solution (or secondary solid solution) of Co phase in WC phase. The La doped powder with grain size of 10nm is obtained after 30h ball milling. A peak of heat release at the temperature of 470℃ was emerged in DTA curve within the range of heating temperature, which showed that the crystal structure relaxation of the powder appeared in the process of high energy ball milling. After consolidated the La doped WC/Co alloy by high energy ball milling exhibits ultra-fine grain sizes and better mechanical properties.

Effect of electric boundary conditions on crack propagation in ferroelectric ceramics

In this paper, the effect of electric boundary conditions on Mode I crack propagation in ferroelectric ceramics is studied by using both linear and nonlinear piezoelectric fracture mechanics. In linear analysis, impermeable cracks under open circuit and short circuit are analyzed using the Stroh formalism and a rescaling method. It is shown that the energy release rate in short circuit is larger than that in open circuit. In nonlinear analysis, permeable crack conditions are used and the nonlinear effect of domain switching near a crack tip is considered using an energy-based switching criterion proposed by Hwang et al.（Acta Metal. Mater.,1995）. In open circuit, a large depolarization field induced by domain switching makes switching much more diffcult than that in short circuit. Analysis shows that the energy release rate in short circuit is still larger than that in open circuit, and is also larger than the linear result. Consequently,whether using linear or nonlinear fracture analysis, a crack is found easier to propagate in short circuit than in open circuit, which is consistent with the experimental observations of Kounga Njiwa et al.（Eng. Fract. Mech., 2006）.

The spin-one Duffin Kemmer Petiau equation in the presence of pseudo-harmonic oscillatory ring-shaped potential

The Duffin-Kemmer-Petiau equation （DKP） is studied in the presence of a pseudo-harmonic oscillatory ring-shaped potential in （1 ＋ 3）-dimensional space-time for spin-one particles. The exact energy eigenvalues and the eigenfunctions are obtained using the Nikiforov-Uvarov method.

Lattice structures and electronic properties of WZ-CuInS2/WZ-CdS interface from first-principles calculations

Using the first-principles plane-wave calculations within density functional theory, the perfect bi-layer and monolayer terminated WZ-CIS （100）/WZ-CdS （100） interfaces are investigated. After relaxation the atomic positions and the bond lengths change slightly on the two interfaces. The WZ-CIS/WZ-CdS interfaces can exist stably, when the interface bonding energies are -0.481 J/m2 （bi-layer terminated interface） and -0.677 J/m2 （monolayer terminated interface）. Via analysis of the density of states, difference charge density and Bader charges, no interface state is found near the Fermi level. The stronger adhesion of the monolayer terminated interface is attributed to more electron transformations and orbital hybridizations, promoting stable interfacial bonds between atoms than those on a bi-layer terminated interface.

RAW MEALS CONTAINING TRACE RE OXIDES TO IMPROVE QUALITY OF CEMENT CLINKER

Clay or industrial wastes containing trace rare earth (RE) oxides as one of the components are used to burn cement clinker. When the total amount of RE oxides reaches 0. 2×10-4 - 2. 0×10-4 (wt), it has positive effect on the burnability of raw meals? and the Alite content in clinker increases. However, with the addition of lan-thanide, the formation process of clinker and the distribu-tion of lanthanide in clinker are different from those of yt-trium. If the burning temperature is 1 450 C , yttrium shiws negative effect on the formation of clinker. There-fore, to improve the quality of cement clinkern, the raw meals in which yttrium content is lower and lanthanide con-tent is higher is preferable; to reduce the consumption of coal, the raw meals that yttrium content is higher is suit-able. Using raw meals containing trace RE oxides can re-duce the cost of fluorite and protect environment.

高级氧化技术应用于冷水机组的现场测试与节能分析

冷水机组冷凝器结垢严重将导致传热性能急剧下降,进而引起机组能耗增加,不利于节能环保。现通过使用高级氧化技术(AOP)可以有效解决冷水机组内的结垢问题,使机组维持在高效的运行状态。通过对实际使用中带AOP装置的冷水机组进行现场测试,并对测试数据进行计算处理分析,进而得出使用AOP处理装置后冷凝器结垢减轻,同时,可对冷水机组进行定量节能效果分析。

Energy Integration in South America Region and the Energy Sustainability of the Nations

The objective of this manuscript is to analyze relation involving the energy sector and socioeco-nomic growth and, then, contextualize the process of energy integration within the development policies in South America. The methodology considers data related to the world’s economy and energy consumption and energy integration policy in countries and regions;and, South America’s energy potential and the energy integration process. Results show that despite the political and institutional difficulties involving the process, energy integration can bring a lot of benefits for countries development. The process of energy integration in South America is divided in three moments, but in both periods the transnational energy projects were restricted, mostly, by a bi-lateral plan and the creation of physical links in a region. In the 21th century’s context, it should be noted Brazil’s participation which has been consolidated as a lead country in this process, and, also the IIRSA (Initiative for the Integration of Regional Infrastructure in South America, nowadays renamed as COSIPLAN) like the main initiative in energy integration in the continent, in a context where the projects are no longer limited to traditional economic blocs. Finally, we note a lack of consensus in defining a comprehensive model of integration and solving asymmetries both within countries and between them.

Energy Optimisation in Wireless Sensor Network

The solution we propose optimizes the energy inside the wireless sensor network (WSN) with higher performance. The WSN is composed of many sensors nodes which collect the information, treat that information then send it to the base station. The information is received by the base station (BS) then data?are?sent to the users by that BS. The most important element in sensor node is energy, as the lifetime of wireless sensor network depends on the sensor node energy. So many researches had been made in order to improve this energy basing routing protocols. As a result, we are able to propose a solution that optimizes this energy. In this paper, we are presenting a new approach of selecting node sensor base on routing protocol and process to send data to the base station. This ameliorates wireless sensor network lifetime and increases?the transmission sensor node to base station.

Recent Development and Application of Geothermal Heat Pump Systems in Cold-Climate Regions of the US: A Further Investigation

A Geothermal Heat Pump (GHP) system is known to have enormous potential for building energy savings and the reduction of associated greenhouse gas emissions, due to its high Coefficient Of Performance (COP). The use of a GHP system in cold-climate regions is more attractive owing to its higher COP for heating compared to conventional heating devices, such as furnaces or boilers. Many factors, however, determine the operational performance of an existing GHP system, such as control strategy, part/full-load efficiency, the age of the system, defective parts, and whether or not regular maintenance services are provided. The omitting of any of these factors in design and operation stages could have significant impacts on the normal operation of GHP systems. Therefore, the objectives of this paper are to further investigate and study the existing GHP systems currently used in buildings located in cold-climate regions of the US, in terms of system operational performance, potential energy and energy cost savings, system cost information, the reasons for installing geothermal systems, current operating difficulties, and owner satisfaction to date. After the comprehensive investigation and in-depth analysis of 24 buildings, the results indicate that for these buildings, about 75% of the building owners are very satisfied with their GHP systems in terms of noise, cost, and indoor comfort. About 71% of the investigated GHP systems have not had serious operating difficulties, and about 85% of the respondents (building owners) would suggest this type of system to other people. Compared to the national median of energy use and energy cost of typical buildings of the same type nationwide, the overall performance of the actual GHP systems used in the cold-climate regions is slightly better, i.e. about 7.2% energy savings and 6.1% energy cost savings on average.

Photon Can Be Described as the Normalized Mutual Energy Flow

Einstein guessed that the macroscopic electromagnetic wave is built by thousands of photons, however, no one has offered a theory about how the macroscopic electromagnetic wave is built from photons. A concrete theory about photons is needed to answer this question. Current theory for photons is Maxwell’s equation which has the solution of waves, but it is difficult to describe the photon as a particle. There is the paradox problem of wave-particle duality. This article offers one solution to solve this problem by introducing the normalized mutual energy flow. The interaction of the retarded wave and advanced wave produce the mutual energy flow. The mutual energy flow satisfies the mutual energy flow theorem. The mutual energy flow theorem tells us that the energy that goes through each surface between the emitter and the absorber is all same. That means the mutual energy flow is different in comparison to the waves. The wave, for example, the retarded wave, its amplitude is decreased with the distance from the source to the point of the field. The mutual energy flow does not decrease. The author noticed this and claimed that the photon is the mutual energy flow. In this article the author updated this claim that the photon is the normalized mutual energy flow. Here the normalization of mutual energy flow will normalize the mutual energy flow to the energy of a photon, which is E = hf. E is the energy of the photon;h is Planck constant;f is the frequency of the light. This normalization is similar to the normalization in quantum mechanics. After this normalization the relation between an electromagnetic wave and photon as a particle becomes clear. This article will prove that the macroscopic wave of an electromagnetic field can be built by thousands of normalized mutual energy flows, which describes the photons. The mutual energy flow is an interaction of the retarded wave and the advanced wave. The retarded wave and the advanced wave satisfy the Maxwell equations. There are two additional waves which are the time-reversal waves which satisfy time-reversal Maxwell equations. The advanced wave and the two time-reversal waves are all real and physical electromagnetic fields. The time-reversal waves cancel all self-energy flows of the retarded wave and advanced wave. Hence, the waves do not carry any energy, the energy is only transferred by the normalized mutual energy flows which are the photons. Hence, all energy is transferred by the photon instead of waves. This offers a solution to paradox of the duality of wave-particle.

Synthesis and Characterization of Comb-like P（MPEGA-co-AM） Copolymer as Phase Change Materials

Comb-like acrylic acid poly（ethylene glycol） methyl ether ester （MPEGA）-co-acrylamide （AM） copolymer [P（MPEGA-co-AM）] as novel phase change materials （PCMs） was successfully synthesized via free-radical water solution polymerization. The structures of P（MPEGA-co-AM） was characterized by Fourier Transform Infrared （FT-lR）. The experimental results showed that P（MPEGA-co-AM） copolymer possessed high molecular weight （Mo =66 kg/mol）, narrow molecular weight distribution （PDI≈1.14）. The phase transition temperature of copolymer decreases to 31℃, which is very much appreciated and urgently needed for smart PCM related to human body. Moreover, P（MPEGA-co-AM） had good thermal stability even at 380℃.

Collaborative Distributed AC Optimal Power Flow: A Dual Decomposition Based Algorithm

We propose a dual decomposition based algorithm that solves the AC optimal power flow(ACOPF) problem in the radial distribution systems and microgrids in a collaborative and distributed manner. The proposed algorithm adopts the second-order cone program(SOCP) relaxed branch flow ACOPF model. In the proposed algorithm, bus-level agents collaboratively solve the global ACOPF problem by iteratively sharing partial variables with its 1-hop neighbors as well as carrying out local scalar computations that are derived using augmented Lagrangian and primal-dual subgradient methods. We also propose two distributed computing platforms, i. e., high-performance computing(HPC) based platform and hardware-in-theloop(HIL) testbed, to validate and evaluate the proposed algorithm. The computation and communication performances of the proposed algorithm are quantified and analyzed on typical IEEE test systems. Experimental results indicate that the proposed algorithm can be executed on a fully distributed computing structure and yields accurate ACOPF solution. Besides, the proposed algorithm has a low communication overhead.