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71.
Passive daytime radiative cooling technology (DRCT) has recently gained significant attention for its ability to achieve sub-ambient temperature without energy consumption, making it an attractive option for space cooling. The cooling performance can be further improved if radiative cooling materials also exhibit high thermal insulation performance. However, synthesizing radiative cooling materials that possess low thermal conductivity while maintaining mechanical durability remains a challenge. Here, a vapor exchange method is developed to prepare particles-based poly(vinylidene fluoride-co-hexafluoropropylene) sponge materials for scalable and efficient daytime radiative cooling. By tailoring the particle diameter distribution, high solar reflection (94.5%), high infrared emissivity (0.956), and low thermal conductivity (0.048 W m−1 K−1) are achieved, resulting in a sub-ambient cooling of 9.8 °C under direct solar irradiation. Additionally, the sponge material exhibits good mechanical durability, sustaining deformation with a strain up to 40%, making it adaptable to diverse scenarios. A radiative cooling material with mechanical durability and thermal insulation can thus pave the way for large-scale applications of DRCT.  相似文献   
72.
Software-defined networking is an emerging paradigm for supporting flexible network management. In the traditional architecture for a software-defined network (SDN), the controller commonly uses a general routing algorithm such as Open Shortest Path First (OSPF), which chooses the shortest path for communication. This may cause the largest amount of network traffic, especially in large-scale environments. In this paper, we present the design for a novel SDN-based four-tier architecture for scalable secure routing and load balancing. In Tier 1, user authentication is conducted using elliptic curve cryptography (ECC); this avoids unnecessary loads from unauthorized users. In Tier 2, packet classification is performed based on the packet characteristics using the fuzzy analytical hierarchy process (fuzzy AHP), and packets are placed into three individual queues. In Tier 3, scalable secure routing is achieved by selecting the optimal path using the improved particle swarm optimization and ant colony optimization algorithms. With these optimization algorithms, we can adaptively change the number of users, the number of switches, and other parameters. In Tier 4, the recommended secure cluster (multicontroller) management is accomplished using an algorithm that employs modified k-means clustering and a recurrent neural network. Deep reinforcement learning (DRL) is also proposed for updating the controller information. Experimental results are analyzed using the OMNeT++ network simulator, and the evaluated performance displayed improvement over a variety of existing methods in terms of response time (50% to 60%), load (55%), execution time (3.2%), throughput (9.8%), packet loss rate (1.02%), end-to-end delay (50%), and bandwidth consumption (45%).  相似文献   
73.
Bacterial membrane vesicles (BMVs) are bi-layered nanostructures derived from Gram-negative and Gram-positive bacteria. Among other pathophysiological roles, BMVs are critical messengers in intercellular communication. As a result, BMVs are emerging as a promising technology for the development of numerous therapeutic applications. Despite the remarkable progress in unveiling BMV biology and functions in recent years, their successful isolation and purification have been limited. Several challenges related to vesicle purity, yield, and scalability severely hamper the further development of BMVs for biotechnology and clinical applications. This review focuses on the current technologies and methodologies used in BMV production and purification, such as ultracentrifugation, density-gradient centrifugation, size-exclusion chromatography, ultrafiltration, and precipitation. We also discuss the current challenges related to BMV isolation, large-scale production, storage, and stability that limit their application. More importantly, the present work explains the most recent strategies proposed for overcoming those challenges. Finally, we summarize the ongoing applications of BMVs in the biotechnological field.  相似文献   
74.
Low bandgap lead-tin halide perovskites are predicted to be candidates to maximize the performance of single junction and tandem solar cells based on metal halide perovskites. In spite of the tremendous progress in lab-scale device efficiency, devices fabricated with scalable techniques fail to reach the same efficiencies, which hinder their potential industrialization. Herein, a method is proposed that involves a template of a 2D perovskite deposited with a scalable technique (blade coating), which is then converted in situ to form a highly crystalline 3D lead-tin perovskite. These templated grown films are alloyed with stoichiometric ratio and are highly oriented with the (l00) planes aligning parallel to the substrate. The low surface/volume ratio of the obtained single-crystal-like films contributes to their enhanced stability in different environments. Finally, the converted films are demonstrated as active layer for solar cells, opening up the opportunity to develop this scalable technique for the growth of highly crystalline hybrid halide perovskites for photovoltaic devices.  相似文献   
75.
Routing is the most basic and essential operation of any ad hoc network. A mobile ad hoc network presents many challenges, because of the severe resource limitations such as dynamic and varying topology, lack of centralized control, insecure medium, and limited battery power, among others. Therefore, optimization and conservation is the key to success of any ad hoc network operation. In this paper, we propose and define 2 new metrics for ad hoc networks: bandwidth utilization ratio and load index. These metrics can be used as an indicator to measure and monitor the network usability and to improve its efficiency by efficient load distribution. They can be used to predict the additional load that can be accommodated in the network, without causing any congestion or overflows. We also propose a new load balancing routing scheme for ad hoc networks, called efficient load balancing method. This method tries to offset the load on different paths using load index as a metric. Load index is defined as a measure of a node's degree of involvement in the message routing process, which is indicative of its load. To make this algorithm efficient, we limit our routes to a few efficient ones only. This number of alternate routes used, out of the pool of all available routes, is defined as degree of distribution. Simulation results adequately prove the efficiency of proposed method, vis‐à‐vis 2 other load balancing approaches, and these are verified statistically at 99% confidence interval. A p × q factorial design is used to verify that simulation results are the actual measurements and not due to some unknown errors.  相似文献   
76.
Big volume changes, the shuttle effect, and poor conductivity are well-known, critical issues of sulfur electrodes that prevent practical application of lithium-sulfur batteries. The design of active materials with a conductive shell provides an effective solution. Traditional strategies have long been limited for practical applications; however, by low productivity and time/energy consuming template-based methods. Here, a facile template-free self-caging nanotechnology for the scalable fabrication of graphene@sulfur nanocages with atomic-scale shells is reported. To do that, a new sulfur-graphene nanochemistry based on a reductive sulfur solution and oxidative sulfonated-graphene dispersion is developed for the first time. With only the help of mechanical mixing, sulfur particles are successfully synthesized in situ and encapsulated into reaction-induced self-assembled sulfonated-graphene nanocages. These unique nanocages not only provide accommodation of the big volume changes in the active materials, but also exhibit robust polysulfide trapping capability due to the synergistic effects from physical blocking and strong chemical absorption. As a result, the resultant sulfur cathodes deliver superior electrochemical performance and have shown an extremely slow capacity decay of 0.019% per cycle at 0.5 C for over 2000 cycles. This study introduces a new self-caging nanochemistry for scalable synthesis of functional nanocages with significant applications beyond lithium-sulfur batteries.  相似文献   
77.
On Using Twisted-Ring Counters for Test Set Embedding in BIST   总被引:2,自引:0,他引:2  
We present a novel built-in self-test (BIST) architecture for high-performance circuits. The proposed approach is especially suitable for embedding precomputed test sets for core-based systems since it does not require a structural model of the circuit, either for fault simulation or for test generation. It utilizes a twisted-ring counter (TRC) for test-per-clock BIST and is appropriate for high-performance designs because it does not add any mapping logic to critical functional paths. Test patterns are generated on-chip by carefully reseeding the TRC. We show that a small number of seeds is adequate for generating test sequences that embed complete test sets for the ISCAS benchmark circuits.Instead of being stored on-chip, the seed patterns can also be scanned in using a low-cost, slower tester. The seeds can be viewed as an encoded version of the test set that is stored in tester memory. This requires almost 10X less memory than compacted test sets obtained from ATPG programs. This allows us to effectively combine high-quality BIST with external testing using slow testers. As the cost of high-speed testers increases, methodologies that facilitate testing using slow testers become especially important. The proposed approach is a step in that direction.  相似文献   
78.
ABSTRACT

A simple and scalable finite-dimensional model based on the port-Hamiltonian framework is proposed to describe the fluid–structure interaction in tubes with time-varying geometries. For this purpose, the moving tube wall is described by a set of mass-spring-damper systems while the fluid is considered as a one-dimensional incompressible flow described by the average momentum dynamics in a set of incompressible flow sections. To couple these flow sections small compressible volumes are defined to describe the pressure between two adjacent fluid sections. The fluid-structure coupling is done through a power-preserving interconnection between velocities and forces. The resultant model includes external inputs for the fluid and inputs for external forces over the mechanical part that can be used for control or interconnection purposes. Numerical examples show the accordance of this simplified model with finite-element models reported in the literature.  相似文献   
79.
分析了现有指标不能评价大规模可扩展交换网络顽健性的问题,结合可扩展交换网络拓扑特性和故障模型,提出了一种基于故障影响的顽健性评价方法,并进一步提出了该方法评价指标的优化算法.通过实验比较了故障影响方法与现有方法对于可扩展交换网络的评价效果,结果表明故障影响方法可以有效地评价大规模可扩展交换网络的顽健性.  相似文献   
80.
This communication reports a strategy for scale‐up of an in situ polymerization technique for polyolefin‐based nanocomposites preparation, taking layered silicate (clay) and multi‐walled carbon nanotubes (MWCNTs) as examples of nanofillers. The strategy is realized by transforming the nanofillers into granular “nanosupports” for Ziegler‐Natta catalysts. With a catalyst to polymer replication effect on particle morphology, the in situ prepared nanocomposites are of controlled granular particle morphology. With the polymer particle morphology controlled, the in situ polymerization technique becomes suitable for industrial olefin polymerization processes for mass production of polyolefin nanocomposites.

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