Multistage Expansion Planning of Active Distribution Systems: Towards Network Integration of Distributed Energy Resources

Over the last few years, driven by several technical and environmental factors, there has been a growing interest in the concept of active distribution networks (ADNs). Based on this new concept, traditional passive distribution networks will evolve into modern active ones by employing distributed energy resources (DERs) such as distributed generators (DGs), energy storage systems (ESSs), and demand responsive loads (DRLs). Such a transition from passive to active networks poses serious challenges to distribution system planners. On the one hand, the ability of DGs to directly inject active and reactive powers into the system nodes leads to bidirectional power flows through the distribution feeders. This issue, if not adequately addressed at the design stage, can adversely affect various operational aspects of ADNs, specifically the reactive power balance and voltage regulation. Therefore, the new context where DGs come into play necessitates the development of a planning methodology which incorporates an accurate network model reflecting realistic operational characteristics of the system. On the other hand, large-scale integration of renewable DGs results in the intermittent and highly volatile nodal power injections and the implementation of demand response programs further complicates the long-term predictability of the load growth. These factors introduce a tremendous amount of uncertainty to the planning process of ADNs. As a result, effective approaches must also be devised to properly model the major sources of uncertainty. Based on the above discussion, successful transition from traditional passive distribution networks to modern active ones requires a planning methodology that firstly includes an accurate network model, and secondly accounts for the major sources of uncertainty. However, incorporating these two features into the planning process of ADNs is a very complex task and requires sophisticated mathematical programming techniques that are not currently available in the literature. Therefore, this research project aim to develop a comprehensive planning methodology for ADNs, which is capable of dealing with different types of DERs (i.e., DGs, ESSs, and DRLs), while giving full consideration to the above-mentioned two key features. To achieve this objective, five major steps are defined for the project. Step 1 develops a deterministic mixed-integer linear programming (MILP) model for integrated expansion planning of distribution network and renewable/conventional DGs, which includes a highly accurate network model based on a linear format of AC power flow equations. This MILP model can be solved using standard off-the-shelf mathematical programming solvers that not only guarantee convergence to the global optimal solution, but also provide a measure of the distance to the global optimum during the solution process. Step 2 proposes a distributionally robust chance-constrained programming approach to characterize the inherent uncertainties of renewable DGs and loads. The key advantage of this approach is that it requires limited information about the uncertain parameters, rather than perfect knowledge of their probability distribution functions. Step 3 devises a fast Benders decomposition-based solution procedure that paves the way for effective incorporation of ESSs and DRLs into the developed planning methodology. To this end, two effective acceleration strategies are proposed to significantly enhance the computational performance of the classical Benders decomposition algorithm. Eventually, Steps 4 and 5 propose appropriate models for ESSs and DRLs and integrate them into the developed planning methodology. In this regard, a sequential-time power flow simulation method is also proposed to incorporate the short-term operation analysis of ADNs into their long-term planning studies. By completing the above-defined steps, the planning model developed in Step 1 will be gradually evolved, so that Step 5 will yield the final comprehensive planning methodology for ADNs

Buckling load analysis of cracked curved beams using differential quadrature element method

This paper investigates the buckling load of a cracked curved beam subjected to external excitations considering the effects of shear deformations and the geometric nonlinearity due to large deformations. The governing nonlinear equations of motion are derived. The solution consists of just static part, leading to nonlinear differential equations. The differential quadrature element method has been used to solve the problem. First, it is applied to the equilibrium equations, leading to a nonlinear algebraic system of equations that will be solved utilizing an arc length strategy. To verify the validity of the proposed method, the beam is modeled using the finite element method. The great agreement between the results shows the accuracy of the proposed method in predicting the loading of buckling of the beam

Edge currents as a probe of the strongly spin-polarized topological noncentrosymmetric superconductors

Recently the influence of antisymmetric spin-orbit coupling has been studied in novel topological superconductors such as half-Heuslers and artificial hetero-structures. We investigate the effect of Rashba and/or Dresselhaus spin-orbit couplings on the band structure and topological properties of a two-dimensional noncentrosymetric superconductor. For this goal, the topological helical edge modes are analyzed for different spin-orbit couplings as well as for several superconducting pairing symmetries. To explore the transport properties, we examine the response of the spin-polarized edge states to an exchange field in a superconductor-ferromagnet heterostructure. The broken chiral symmetry causes the uni-directional currents at opposite edges.Comment: 10 pages, 7 figure

Analysis and Comparison of Modern Video Compression Standards for Random-access Light-field Compression

Light-field (LF) 3D displays are anticipated to be the next-generation 3D displays by providing smooth motion parallax, wide field of view (FOV), and higher depth range than the current autostereoscopic displays. The projection-based multi-view LF 3D displays bring the desired new functionalities through a set of projection engines creating light sources for the continuous light field to be created. Such displays require a high number of perspective views as an input to fully exploit the visualization capabilities and viewing angle provided by the LF technology. Delivering, processing and de/compressing this amount of views pose big technical challenges. However, when processing light fields in a distributed system, access patterns in ray space are quite regular, some processing nodes do not need all views, moreover the necessary views are used only partially. This trait could be exploited by partial decoding of pictures to help providing less complex and thus real-time operation. However, none of the recent video coding standards (e.g., Advanced Video Coding (AVC)/H.264 and High Efficiency Video Coding (HEVC)/H.265 standards) provides partial decoding of video pictures. Such feature can be achieved by partitioning video pictures into partitions that can be processed independently at the cost of lowering the compression efficiency. Examples of such partitioning features introduced by the modern video coding standards include slices and tiles, which enable random access into the video bitstreams with a specific granularity. In addition, some extra requirements have to be imposed on the standard partitioning tools in order to be applicable in the context of partial decoding. This leads to partitions called self-contained which refers to isolated or independently decodable regions in the video pictures. This work studies the problem of creating self-contained partitions in the conventional AVC/H.264 and HEVC/H.265 standards, and HEVC 3D extensions including multi-view (i.e., MV-HEVC) and 3D (i.e., 3D-HEVC) extensions using slices and tiles, respectively. The requirements that need to be fulfilled in order to build self-contained partitions are described, and an encoder-side solution is proposed. Further, the work examines how slicing/tiling can be used to facilitate random access into the video bitstreams, how the number of slices/tiles affects the compression ratio considering different prediction structures, and how much effect partial decoding has on decoding time. Overall, the experimental results indicate that the finer the partitioning is, the higher the compression loss occurs. The usage of self-contained partitions makes the decoding operation very efficient and less complex

Review on Effect of Bupropion on Attenuates Methamphetamine Self-administration in Adult Male Rat

Introduction: Methamphetamine is a highly potent, addictive drug that is widely abused in many countries around the world. Methamphetamine produces a general state of well-being along with increased wakefulness, talkativeness, and physical activity and decreased appetite. Behavioral treatment programs have had some success in the treatment of methamphetamine addiction, yet many patients continue to relapse after repeatedly seeking treatment. Thus, pharmacotherapies treatments for methamphetamine addiction are being evaluated. Bupropion is an atypical antidepressant with stimulant properties. This drug has been used off-label to treat methamphetamine addicts, thus prompting the need for systematic investigations of its efficacy. Methods and Results:Male wistar rats, weighing 200–250 g (8 weeks old) at the start of the experiment. In the self-administration study, rats were surgically prepared with indwelling jugular catheters. After the surgery rats were trained to press a lever of methamphetamine reinforcement (0.05 mg/kg/injection) in operant boxes under baseline conditions. When responding stabilized, rats entered the acute testing phase. Each rat was tested with a unique order of vehicle, 10, 30, and 60 mg/kg bupropion. Each solution was administered IP 5 min before placement in the chamber for a regular self-administration session and each test was separated by at least 2 maintenance days of methamphetamine self-administration without drug pretreatment. Bupropion pretreatment appeared to decrease active lever responding. Consistent with the active lever data, rats treated with 60 mg/kg bupropion took significantly fewer total methamphetamine infusions in comparison to the other 2 groups. When Control rats (n=6) (i.e., those pretreated with saline in the previous phase) were given an acute injection of 30 mg/kg bupropion, lever pressing decreased. Conclusions: Several questions remain about bupropion’s impact during withdrawal, abstinence, and relapse in a preclinical setting. Research investigating these aspects of addiction will help provide a clearer picture on the effects of bupropion on methamphetamine self-administration in laboratory animals and methamphetamine abuse in humans

PCl5 as a mild and efficient catalyst for the synthesis of bis(indolyl)methanes and di-bis(indolyl)methanes

Phosphorus pentachloride (PCl5) can efficiently catalyze the condensation of indoles with aldehydes as well as ketones at room temperature to afford bis(indolyl)methanes and di-bis(indolyl)methanes in high yields and short reaction times. KEY WORDS: PCl5, bis(Indolyl)methane, di-bis(Indolyl)methane, Indole, Aldehyde, Ketone  Bull. Chem. Soc. Ethiop. 2008, 22(3), 453-458

Influence of Fracture Heterogeneity Using Linear Congruential Generator (LCG) on the Thermal Front Propagation in a Single Geothermal Fracture-Rock Matrix System

An implicit finite difference numerical model has been developed to investigate the influence of fracture heterogeneity on the propagation of thermal front in a single horizontal fracture-matrix system. Instead of depending on a complex and data-demanding geostatistical method for a precise representation of fracture aperture, a statistical linear congruential generator (LCG) method was applied in the present study to replicate the unpredictable nature of fracture aperture morphology. The results have been compared with the parallel plate model and simple sinusoidal model. Finally, sensitivity analysis of fracture aperture size and fluid flow rate has been carried out to identify the conditions at which fracture heterogeneity is critical. The results indicate that LCG-aperture enhances the heat transfer between fracture and hot rock matrix compared to the parallel and sinusoidal fractures. Further, the temperature profiles in hot rock indicate that there was a greater loss of heat for the case of LCG-aperture (25% loss) compared to sinusoidal (16%) and parallel plate (8%) apertures. It was found that heterogeneity does not play a major role at small fracture aperture size (≤50 μm) and at low flow rates. However, as fracture aperture size increases, the heterogeneity plays a vital part even at low flow rates.publishedVersio