556 research outputs found
Market-based Control of Air-Conditioning Loads with Switching Constraints for Providing Ancillary Services
Air-conditioning loads (ACLs) are among the most promising demand side
resources for their thermal storage capacity and fast response potential. This
paper adopts the principle of market-based control (MBC) for the ACLs to
participate in the ancillary services. The MBC method is suitable for the
control of distributed ACLs because it can satisfy diversified requirements,
reduce the communication bandwidth and protect users' privacy. The modified
bidding and clearing strategies proposed in this paper makes it possible to
adjust the switching frequency and strictly satisfy the lockout time constraint
for mechanical wear reduction and device protection, without increasing the
communication traffic and computational cost of the control center. The
performance of the ACL cluster in two typical ancillary services is studied to
demonstrate the effect of the proposed method. The case studies also
investigate how the control parameters affect the response performance, comfort
level and switching frequency.Comment: 5 pages, conferenc
Experimental Study on the Effectiveness of Extracurricular Football Training for Improving Primary Students Physical Fitness
The purpose of this study is to examine the effectiveness of after-school football training in improving the physical fitness of primary school students, so as to provide corresponding Suggestions for carrying out after-school football training in primary schools. A total of 72 students from the experimental primary school of Mouping district, Yantai city, Shandong province, participated in this experimental study, including 36 in the experimental group and 36 in the control group.The experiment was conducted for two semesters. During the experiment period, the experimental group conducted one-hour football training after school from Monday to Thursday afternoon every week, and two hours of football training on Saturday morning every week. The control group conducted sports teaching and extracurricular activities as usual without other intervention. Before and after the experiment, both the experimental group and the control group underwent physical fitness tests according to the physical fitness test standards of Chinese students, including lung capacity, 50-meter run, one-minute skipping rope, sitting forward flexor, and one-minute sit-ups. The test results were all converted to the 100-point system according to the scoring standards. Before the experiment, there was no significant difference between the experimental group and the control group in various physical fitness indicators (p \u3e 0.05). After the experiment, the lung capacity score (T = 3.108, p \u3c 0.05), the 50-meter run score (T = 6.593, p \u3c 0.05), the skipping score (T = 9.227, p \u3c 0.05), the sitting forward flexor score (T = 3.742, p \u3c 0.05), and the sit-up score (T = 5.210, p \u3c 0.05) of the experimental group were significantly higher than that of the control group. This study shows that the physical fitness of primary school students can be improved by football training in their spare time. It is suggested to carry out after-school football training activities in primary schools so as to effectively improve the physical fitness of pupils
Stream privacy amplification for quantum cryptography
Privacy amplification is the key step to guarantee the security of quantum
communication. The existing security proofs require accumulating a large number
of raw key bits for privacy amplification. This is similar to block ciphers in
classical cryptography that would delay the final key generation since an
entire block must be accumulated before privacy amplification. Moreover, any
leftover errors after information reconciliation would corrupt the entire
block. By modifying the security proof based on quantum error correction, we
develop a stream privacy amplification scheme, which resembles the classical
stream cipher. This scheme can output the final key in a stream way, prevent
error from spreading, and hence can put privacy amplification before
information reconciliation. The stream scheme can also help to enhance the
security of trusted-relay quantum networks. Inspired by the connection between
stream ciphers and quantum error correction in our security analysis, we
further develop a generic information-theoretic tool to study the security of
classical encryption algorithms.Comment: 21 pages, 8 figure
A mutator phenotype promoting the emergence of spontaneous oxidative stress-resistant mutants in Campylobacter jejuni
Campylobacter jejuni is a leading cause of foodborne illnesses worldwide. As a microaerophilic organism, C. jejuni must be able to defend against oxidative stress encountered both in the host and in the environment. How Campylobacter utilizes a mutation-based mechanism for adaptation to oxidative stress is still unknown. Here we present a previously undescribed phenotypic and genetic mechanism that promotes the emergence of oxidative stress resistant mutants. Specifically, we showed that a naturally occurring mutator phenotype, resulting from a loss of function mutation in the DNA repair enzyme MutY, increased oxidative stress resistance (OXR) in C. jejuni. We further demonstrated that MutY malfunction didn\u27t directly contribute to the OXR phenotype, but increased the spontaneous mutation rate in the peroxide regulator gene perR, which functions as a repressor for multiple genes involved in oxidative stress resistance. Mutations in PerR resulted in loss of its DNA binding function and derepression of PerR-controlled oxidative stress defense genes, thereby conferring an OXR phenotype and facilitating Campylobacter survival under oxidative stress. These findings reveal a new mechanism that promotes the emergence of spontaneous OXR mutants in bacterial organisms
Recent Advances of ZnO-Based Perovskite Solar Cell
Perovskite solar cells (PSCs) have developed rapidly over the past few years, and the power conversion efficiency (PCE) of PSCs has exceeded 25%. It has the characteristics of low cost, high efficiency, simple process and so on, and hence has a good development prospect. Due to the difference in electrons and holes diffusion lengths, electron transporting materials (ETMs) play a crucial role in the performance of PSCs. ZnO electron transport layer (ETL) has the advantages of high electron mobility, high transmittance, suitable energy level matching with neighbor layer in PSCs, low temperature preparation and environmental friendliness, so it has become the main application material of electron transport layer in perovskite solar cells. In this review, the application of ZnO-ETMs in PSCs in recent years is reviewed, and the effect of ZnO-ETMs on the performance of PSCs is also introduced. Finally, the limitations of ZnO-ETMs based PSCs and the methods to solve these problems are discussed, and the development prospect of PSCs is prospected
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