(M)Unc13s in Active Zone Diversity: A Drosophila Perspective

The so-called active zones at pre-synaptic terminals are the ultimate filtering devices, which couple between action potential frequency and shape, and the information transferred to the post-synaptic neurons, finally tuning behaviors. Within active zones, the release of the synaptic vesicle operates from specialized “release sites.” The (M)Unc13 class of proteins is meant to define release sites topologically and biochemically, and diversity between Unc13-type release factor isoforms is suspected to steer diversity at active zones. The two major Unc13-type isoforms, namely, Unc13A and Unc13B, have recently been described from the molecular to the behavioral level, exploiting Drosophila being uniquely suited to causally link between these levels. The exact nanoscale distribution of voltage-gated Ca2+ channels relative to release sites (“coupling”) at pre-synaptic active zones fundamentally steers the release of the synaptic vesicle. Unc13A and B were found to be either tightly or loosely coupled across Drosophila synapses. In this review, we reported recent findings on diverse aspects of Drosophila Unc13A and B, importantly, their nano-topological distribution at active zones and their roles in release site generation, active zone assembly, and pre-synaptic homeostatic plasticity. We compared their stoichiometric composition at different synapse types, reviewing the correlation between nanoscale distribution of these two isoforms and release physiology and, finally, discuss how isoform-specific release components might drive the functional heterogeneity of synapses and encode discrete behavior.

Coupled Fluid-Thermal Investigation on Drag and Heat Reduction of a Hypersonic Spiked Blunt Body with an Aerodisk

In the traditional investigations on the drag and heat reduction of hypersonic spiked models, only the aerodynamic calculation is performed, and the structural temperature cannot be obtained. This paper adopted the loosely coupled method to study its efficiency of drag and heat reduction, in which the feedback effect of wall temperature rise on aeroheating is considered. The aeroheating and structural temperature were obtained by the CFD and ABAQUS software respectively. The coupling analysis of the hypersonic circular tube was carried out to verify the accuracy of the fluid field, the structural temperature, and the coupled method. Compared with experimental results, the calculated results showed that the relative errors of stagnation heat flux and stagnation temperature were 1.34% and 4.95% respectively, and thus the effectiveness of the coupled method was verified. Installing a spike reduced the total drag of the forebody. The spiked model with an aerodisk reduced the aeroheating of the forebody, while the model without an aerodisk intensified the aeroheating. The spiked model with a planar aerodisk had the best performance on drag and heat reduction among all the models. In addition, increasing the length of the spike reduced the drag and temperature of the forebody. With the increase of the length, the change rates of drag, pressure, heat flux, and temperature decreased gradually. Increasing the diameter of the aerodisk also reduced the temperature of the forebody, while the efficiency of forebody drag reduction first increased and then decreased. In conclusion, the heat and drag reduction must be considered comprehensively for the optimal design of the spike.

Dual-Side Phase-Shift Control for Strongly Coupled Series–Series Compensated Electric Vehicle Wireless Charging Systems

Wireless power transfer (WPT) for electric vehicles is an emerging technology and a future trend. To increase power density, the coupling coefficient of coils can be designed to be large, forming a strongly coupled WPT system, different from the conventional loosely coupled WPT system. In this way, the power density and efficiency of the WPT system can be improved. This paper investigates the dual-side phase-shift control of the strongly coupled series–series compensated WPT systems. The mathematical models based on the conventional first harmonic approximation and differential equations for the dual-side phase-shift control are built and compared. The dual-side phase-shift angle and its impact on the power transfer direction and soft switching are investigated. It is found that synchronous rectification at strong couplings can lead to hard switching because the dual-side phase shift in this case is over 90°. In comparison, a relatively high efficiency and soft switching can be realized when the dual-side phase shift is below 90°. The experimental results have validated the analysis.

Current-Fed Bidirectional DC-DC Converter Topology for Wireless Charging System Electrical Vehicle Applications

This paper compares the efficiency of a modified wireless power transfer (WPT) system with a current-fed dual-active half-bridge converter topology and a complete bridge converter topology for a current-fed resonate compensation network with current sharing and voltage doubler. Full-bridge topologies are widely used in current WPT structures. The C-C-L resonate compensation networks for dual-active half-bridge converter and full-bridge converter topologies are built in this paper on both the transmitter and receiver sides. Due to higher voltage stress around inverter switches, series-parallel (S-P) tanks are not recommended for current-fed topologies because they are not ideal for medium power applications. A series capacitor is connected to reduce the reactive power absorbed by the loosely coupled coil. As a consequence, the C-C-L network is used as a compensation network. Dual-active half-bridge topology is chosen over full-bridge topology due to the system’s component count and overall cost. Soft-switching of the devices is obtained for the load current. The entire system is modelled, and the effects are analysed using MATLAB simulation.

An adaptive authentication and authorization model for service oriented enterprise computing

Service oriented enterprise computing is an integration architectural style aimed to expose and consume coarse grained and fine grained modularization of business functionalities as services that are being deployed in the loosely coupled organizational environment. The web service is the implementation technology of service oriented architecture (SOA) where it is built on the existing networking and web interfacing standards as it has to use the web as a medium of communication and does not have any specialized in-built layer for security. The majority of the vendor security products in the market need specialized hardware/software components, eventually, they break the standards and principles of service oriented architecture. The traditional way of problem solving is not effective for developing security solutions for service oriented computing, as its boundaries keep expanding beyond a single organiza-tional environment due to the advent of communication and business technologies such as the Internet of Things (IoT), hyper-personalization, and edge computing. Hence, it is a mandatory entity in this digital age of enterprise computing to have a specialized authentication and authorization solution exclusively for addressing the existing security gaps in SOA in an adaptive way forward approach. In this paper, the security gaps in the existing Identity and Access Management (IDAM) solutions for service oriented enterprise computing are analyzed, and a novel intelligent security engine which is packed with extended authentication and authorization solution model for service consumption is presented. The authentication and authorization security requirements are considered as cross cutting concerns of SOA implementation and the solution is constructed as Aspect-Oriented Programming (AOP) advices, which enables the solution can be attached as a ‘plug & play’ component without changing the underlying source code of the service implementation. For Proof-of-Concept (PoC), the proposed authentication and authorization security model is tested in a large scale service oriented enterprise computing environment and the results have been analyzed statistically. It is evident from the results that the proposed security model addresses security issues comparatively better than existing security solutions.

Education as Loosely Coupled System of Technology and Pedagogy

The recent development of education seems to be driven mainly by technology; assigning version numbers is an attempt to tame this development. But education is more complex than buzzwords like “Learning 4.0” may suggest. In this article, we argue for viewing education as a loosely coupled system of two interacting layers, technology and pedagogy: closely connected, but not glued together. Using several examples, we show that sometimes technological innovations trigger pedagogical innovations and sometimes pedagogical needs initiate the development of technological solutions. We intend the model of loosely coupled layers of technology and pedagogy as a starting point for opening an overdue discussion on how to make the best use of technology for teaching and learning. We argue that complementing technology with established and proven principles of situated contextualized pedagogy is a key element for the future development of education.