Anomalous Zn2+ Storage Behavior in Dual-Ion-In-Sequence Reconstructed Vanadium Oxides

Vanadium oxides with fast and stable Zn²⁺ storage are of great significance to the development of high-performance aqueous zinc ion batteries (ZIBs), and yet they commonly suffer from structural instability and sluggish diffusion kinetics. Herein, a new “dual-ion-in-sequence” intercalation strategy based on quenching is proposed to address these issues. Interestingly, it is found that the Zn²⁺ storage mechanism evolves from the common solid-state ion diffusion kinetic into an intercalation pseudocapacitance as a result of the enlarged interlayer spacing of V₂O₅. Together with the expanded interlayer spacing arising from the “dual-ion-in-sequence” intercalation, oxygen defects are simultaneously generated at the sub-surface of the reconstructed Li@MnVO materials. Benefitting from the improved ionic diffusivity, intercalation pseudocapacitance, and fast charge transferability, full cell based on Li@MnVO cathode shows impressive rate capability and excellent cycling stability of 5000 cycles with a high energy density of 253 Wh kg^-1 at 10 A g^-1. More importantly, the capacity can maintain at 125 mAh g^-1 at 4 A g^-1 even under a raised mass loading of 10 mg cm^-2. The proposed “dual-ion-in-sequence” intercalation strategy of manipulating V₂O₅ structure at atomic scales is a viable pathway for the high-performance layered metal oxides, not only for ZIBs but also for other energy storage systems.     

Power Mitigation by Performance Equalization in a Heterogeneous Reconfigurable Multicore Architecture

This paper presents an integrated self-aware computing model mitigating the power dissipation of a heterogeneous reconfigurable multicore architecture by dynamically scaling the operating frequency of each core. The power mitigation is achieved by equalizing the performance of all the cores for an uninterrupted exchange of data. The multicore platform consists of heterogeneous Coarse-Grained Reconfigurable Arrays (CGRAs) of application-specific sizes and a Reduced Instruction-Set Computing (RISC) core. The CGRAs and the RISC core are integrated with each other over a Network-on-Chip (NoC) of six nodes arranged in a topology of two rows and three columns. The RISC core constantly monitors and controls the performance of each CGRA accelerator by adjusting the operating frequencies unless the performance of all the CGRAs is optimally balanced over the platform. The CGRA cores on the platform are processing some of the most computationally-intensive signal processing algorithms while the RISC core establishes packet based synchronization between the cores for computation and communication. All the cores can access each other’s computational and memory resources while processing the kernels simultaneously and independently of each other. Besides general-purpose processing and overall platform supervision, the RISC processor manages performance equalization among all the cores which mitigates the overall dynamic power dissipation by 20.7 % for a proof-of-concept test.     

Genetic markers and duodenal ulcer

In the second stage of the reform it is essential to proceed from problems of financing and rewards to health services and their ethic attributes. The dilemma produced by the increasing demands on availability and standard of services on the one hand and efforts to reduce costs on the other leads to the metaphorical "iron triangle of health care", exposed to intense internal tension. The only possibility how to straighten it, which would weaken the danger of crisis, are strict regulatory measures enforced by the State. The foremost task is to define and specify basic (standard) care. As a possible approach the author mentions the Oregon experiment. He draws attention to the phenomenon of "concentration of costs" in the practice of health insurance companies, calling for a major measure of solidarity.     

Security modeling for service-oriented systems using security pattern refinement approach

Security is one of the critical aspects of current systems, which are based on loosely coupled and technology-agnostic service-oriented architectures (SOA). Though SOA is the driving force for enterprises to open their ends for global business collaborations, nevertheless it evolves many challenges for modeling and enforcing security. One of the main problems for designing secure systems is the lack of consistent frameworks and methodologies for modeling security concerns. Traditional approaches consider security at the end of system development, which evolves inflexible and un-configurable systems, which are too difficult to maintain and manage. The other major problem with current approaches is that they assume pre-defined and hard-coded security patterns and mechanisms for secure system design. Whereas, the evolving SOA systems require configurable security to realize different security patterns and security policies in a variety of business scenarios. To solve these problems, it is necessary to model security concerns from the beginning of system modeling in a platform-independent way. This paper proposes a pattern refinement approach for security modeling to achieve configurable and declarative security, based on the principles of abstraction, refinement, separation-of-concerns and maintainability to achieve flexible configurations of SOA security. In the proposed approach, a Domain Expert defines abstract policies using common security vocabulary and a Security Expert models security with patterns and refines them for a target architecture in successive systematic refinements. Furthermore, it facilitates the transformation of abstract security models into executable security policies for the target platforms.     

Comprehensive bandwidth utilization and polling mechanism for XGPON

For an efficient utilization of the upstream bandwidth in passive optical network, a dynamic bandwidth assignment mechanism is necessary as it helps the service providers in provisioning of bandwidth to users according to the service level agreements. The scheduling mechanism of existing schemes, immediate allocation with colorless grant and efficient bandwidth utilization (EBU), does not assign the surplus bandwidth to a specific traffic class and only divides it equally among the optical network units (ONUs). This results in overreporting of ONU bandwidth demand to the optical line terminal and causes wastage of bandwidth and increase in delays at high traffic loads. Moreover, the EBU also assigns the unused bandwidth of lightly loaded ONU queues to the overloaded queues through an Update operation. This Update operation has a flaw that it borrows the extra bandwidth to a queue in the current service interval, if the queue report is higher than its service level agreement and refunds in next service interval. This borrow‐refund operation causes reduced bandwidth allocation to the lower priority classes and increases their delay and frame loss. This study improves both these weaknesses. The simulation results show that the proposed scheme uses bandwidth efficiently and reduces mean upstream delay of type‐2 (T2) traffic class by 38% and type‐3 (T3) up to 150% compared to immediate allocation with colorless grant at a cost of up to 10% higher delay for T2. However, T4 performance improves by 400% compared to EBU with slight increase in delay for T2 traffic class. Overall, it shows a balanced performance for all the traffic classes and minimizes the bandwidth waste per cycle as well as the frame loss rate.     

On spatially disjoint lightpaths in optical networks

Within the communication networks, a delayed constrained data packet is the one that will be dropped if not being served before a certain deadline time, which causes data packet loss affecting the quality of service (QoS). In this paper, we study the blocking probability and the mean delay of such delay constrained packets in an asynchronous single-wavelength optical buffer in optical packet switching networks, where the packet arrival process follows the Poisson process and the packet-length distribution is assumed to be general. We obtain the integral equations of the modeled system and the exact expressions of blocking probabilities and the mean delays. Numerical examples are provided to validate the results with interesting observations being highlighted.     

Application of Metaheuristic Algorithms for Optimizing Longitudinal Square Porous Fins

The objectives of this study involve the optimization of longitudinal porous fins of square cross-section using metaheuristic algorithms. A generalized nonlinear ordinary differential equation is derived using Darcy and Fourier’s laws in the energy balance around a control volume and is solved numerically using RFK 45 method. The temperature of the base surface is higher than the fin surface, and the fin tip is kept adiabatic or cooled by convection heat transfer. The other pertinent parameters include Rayleigh number (100 ≤ Ra ≤ 10⁴), Darcy number, (10⁻⁴ ≤ Da ≤ 10⁻²), relative thermal conductivity ratio of solid phase to fluid (1000 ≤ k_r ≤ 8000), Nusselt number (10 ≤ Nu ≤ 100), porosity (0.1 ≤ φ ≤ 0.9). The impacts of these parameters on the entropy generation rate are investigated and optimized using metaheuristic algorithms. In computer science, metaheuristic algorithms are one of the most widely used techniques for optimization problems. In this research, three metaheuristic algorithms, including the firefly algorithm (FFA), particle swarm algorithm (PSO), and hybrid algorithm (FFA-PSO) are employed to examine the performance of square fins. It is demonstrated that FFA-PSO takes fewer iterations and less computational time to converge compared to other algorithms.     

Effect of Viscous Dissipation and Internal Heat Generation/Absorption on Heat Transfer Flow Over a Moving Wedge With Convective Boundary Condition

In this study, the effects of viscous dissipation and internal heat generation/absorption on heat transfer viscous flow over a moving wedge in the presence of suction or injection with a convective boundary condition have been carried out numerically for various values of dimensionless parameters. With the help of similarity transformation, the momentum and energy equations are reduced to a set of coupled non‐linear ordinary differential equations. These equations are solved using the Runge–Kutta fourth‐order method with a shooting technique. The variation in the dimensionless temperature, velocity, heat transfer coefficient, and shear stress have been presented in tabular as well as in graphical form for a range of controlling parameters. It is shown that the dimensionless heat transfer rate is a strong function of viscous dissipation and convective parameters and heat transfer shows an enhanced behavior with the stretching parameter for both the favorable and unfavorable regimes. It is also shown that in the presence of a heat source, the dimensionless temperature and its gradients in thermal boundary layers are found to be high for a high value of the convection parameter. The comparison of present results with the available data shows a good agreement. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 42(7): 589–602, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21055     

Effect of printing parameters on mechanical properties of extrusion-based additively manufactured ceramic parts

The purpose of this study is to investigate the effect of printing parameters on the physical and mechanical properties of additively manufactured ceramics (alumina and zirconia). Sample parts were obtained by extrusion-based additive manufacturing of a ceramic-binder mixture and subsequent post-processing (debinding and sintering). Their mechanical properties (microhardness, flexural strength, toughness) were measured and correlated with the printing parameters. Part orientation is the most significant factor for microhardness and flexural strength in both ceramic materials. Parts with vertical orientation show higher hardness while horizontal samples show higher flexural strength compared to their respective counterparts. Extrusion velocity was found to be insignificant for hardness and flexural strength. However, a marginal increase in fracture toughness with the increase in the extrusion velocity was observed. The fracture toughness of additively manufactured ceramics shows an increasing trend with elastic modulus and flexural strength and a decreasing trend with hardness and sintered density.