547 research outputs found
A Novel Genetic Algorithm using Helper Objectives for the 0-1 Knapsack Problem
The 0-1 knapsack problem is a well-known combinatorial optimisation problem.
Approximation algorithms have been designed for solving it and they return
provably good solutions within polynomial time. On the other hand, genetic
algorithms are well suited for solving the knapsack problem and they find
reasonably good solutions quickly. A naturally arising question is whether
genetic algorithms are able to find solutions as good as approximation
algorithms do. This paper presents a novel multi-objective optimisation genetic
algorithm for solving the 0-1 knapsack problem. Experiment results show that
the new algorithm outperforms its rivals, the greedy algorithm, mixed strategy
genetic algorithm, and greedy algorithm + mixed strategy genetic algorithm
Mixed strategy may outperform pure strategy: An initial study
In pure strategy meta-heuristics, only one search strategy is applied for all
time. In mixed strategy meta-heuristics, each time one search strategy is
chosen from a strategy pool with a probability and then is applied. An example
is classical genetic algorithms, where either a mutation or crossover operator
is chosen with a probability each time. The aim of this paper is to compare the
performance between mixed strategy and pure strategy meta-heuristic algorithms.
First an experimental study is implemented and results demonstrate that mixed
strategy evolutionary algorithms may outperform pure strategy evolutionary
algorithms on the 0-1 knapsack problem in up to 77.8% instances. Then
Complementary Strategy Theorem is rigorously proven for applying mixed strategy
at the population level. The theorem asserts that given two meta-heuristic
algorithms where one uses pure strategy 1 and another uses pure strategy 2, the
condition of pure strategy 2 being complementary to pure strategy 1 is
sufficient and necessary if there exists a mixed strategy meta-heuristics
derived from these two pure strategies and its expected number of generations
to find an optimal solution is no more than that of using pure strategy 1 for
any initial population, and less than that of using pure strategy 1 for some
initial population
Brzo otkrivanje uzročnika virusnog proljeva goveda u mlijeku iz spremnika pomoću kombinacije metoda umnožene rekombinazne polimeraze i test-traka za „lateral flow“ analizu
Bovine viral diarrhea virus (BVDV) is one of the most prevalent and economically important pathogens of ruminants, and leads to significant financial losses to the livestock industry worldwide. Development of rapid and accurate diagnostic methods is of great importance for the control and eradication of BVDV infection. The aim of this study was to develop a novel isothermal recombinase polymerase amplification (RPA) method combined with a lateral flow dipstick (LFD), for rapid detection of BVDV. RPA primers and a probe targeting the specific conserved 5′-UTR of BVDV genome were designed. The RPA amplification could be finished at a constant temperature of 38 0000C for 15 min, and the amplification product was easily visualized on a simple LFD within 5 min. The detection limit of this assay was 20 copies per reaction, and there was no cross-reactivity with other bovine infectious viruses, such as infectious bovine rhinotracheitis virus (IBRV), bovine enterovirus (BEV), bovine coronavirus (BcoV), bovine parainfluenza virus type 3 (BPIV-3), bovine ephemeral fever virus (BEFV) and bovine respiratory syncytial virus (BRSV). The assay performance on bulk tank milk was also evaluated, and the sensitivity and accuracy of BVDV LFD RPA was compared with real-time RT-PCR. Of 284 pool or bulk tank milk samples, 51 were found to be positive by RPA assay, whereas 52 were positive by real-time RT-PCR. The coincidence rate between LFD RPA and real-time RT-PCR was 97.54% (277/284).Uzročnik virusnog proljeva goveda (BVDV) jedan je od najčešćih i ekonomski važnih patogena preživača koji uzrokuje znatne financijske gubitke u stočarskoj industriji širom svijeta. Razvoj brzih i točnih dijagnostičkih metoda iznimno je važan za kontrolu i iskorjenjivanje zaraze BVDV-om. Cilj ovog istraživanja bio je razviti novu metodu za brzo otkrivanje BVDV-a baziranu na kombinaciji metoda umnožene rekombinazne polimeraze i test-traka za „lateral flow“ analizu. Oblikovane su početnice i probe za umnažanje rekombinazne polimeraze usmjerene na specifični konzervirani 5’-UTR u genomu BVDV-a. Umnažanje se moglo završiti pri konstantnoj temperaturi od 38 °C tijekom 15 minuta i produkt umnažanja je lako vizualiziran na jednostavnoj test-traci za „lateral flow“ analizu unutar 5 minuta. Test je ograničen na 20 kopija po reakciji, pri čemu nije bilo križne reaktivnosti s drugim goveđim zaraznim virusima kao što su infektivni rinotraheitis virusa goveda (IBRV), goveđi enterovirus (BEV), goveđi koronavirus (BcoV), virus goveđe parainfluence tipa 3 (BPIV-3), virus gljivične ephemeralne groznice (BEFV) i goveđi respiratorni sincicijski virus (BRSV). Učinkovitost kombinacije navedenih metoda istražena je i s obzirom na usporedbu osjetljivosti odnosno točnosti koja se dobiva uporabom RT-PCR metode. Od 284 skupna uzorka mlijeka iz spremnika, kombinacijom metoda umnožene rekombinazne polimeraze i test-traka za „lateral flow“ analizu utvrđen je 51 pozitivan uzorak, a RT-PCR 52 pozitivna uzorka. Stopa podudarnosti između navedenih metoda bila je 97,54 % (277/284)
Directly Observing the Reversible Unfolding and Refolding of an Alpha/Beta Protein by Single-Molecule Atomic Force Microscopy
Digitalitzat per Artypla
Highly pathogenic avian influenza A virus H5N1 NS1 protein induces caspase-dependent apoptosis in human alveolar basal epithelial cells
<p>Abstract</p> <p>Background</p> <p>It is widely considered that the multifunctional NS1 protein of influenza A viruses contributes significantly disease pathogenesis by modulating a number of virus and host-cell processes, but it is highly controversial whether this non-structural protein is a proapoptotic or antiapoptotic factor in infected cells.</p> <p>Results</p> <p>NS1 protein of influenza A/chicken/Jilin/2003 virus, a highly pathogenic H5N1 strain, could induce apoptosis in the carcinomic human alveolar basal epithelial cells (A549) by electron microscopic and flow cytometric analyses. NS1 protein-triggered apoptosis in A549 cells is via caspase-dependent pathway.</p> <p>Conclusions</p> <p>Influenza A virus NS1 protein serves as a strong inducer of apoptosis in infected human respiratory epithelial cells and plays a critical role in disease pathogenesis.</p
Coordinating Multiple Resources for Optimal Postdisaster Operation of Interdependent Electric Power and Natural Gas Distribution Systems
Electric power and natural gas systems are not separated but rather are
increasingly connected physically and functionally interdependent due to the
continuing development of natural gas-fired generation and gas industry
electrification. Such interdependency makes these two systems interact with
each other when responding to disasters. The aggravated risk of cascading
failures across the two systems has been exposed in recent energy crises,
highlighting the significance of preparing these interdependent systems against
disasters and helping their impacted services quickly recover. This promotes us
to treat power and gas systems as one whole to fully capture their interactive
behaviors. In this paper, we focus on the interdependent electric power and
natural gas distribution systems (IENDS) and propose a "supply - demand -
repair" strategy to comprehensively help the IENDS tide over the emergency
periods after disasters by coordinating mobile or stationary emergency
resources for various uses. Specifically, 1) on the supply side, the fuel
supply issue of different types of generators for emergency use is considered
and the fuel delivery process among different fuel facilities is mathematically
formulated; 2) on the demand side, a zonewise method is proposed for integrated
dispatch of power and gas demand responses; and 3) in the repair process, a
varying efficiency related to the repair units at work is introduced to
accurately model repairs. The proposed strategy is formulated into a
mixed-integer second-order cone programming model to obtain a globally optimal
decision of deploying all of those resources in a coordinated and organized
manner. A series of case studies based on test systems are conducted to
validate the effectiveness of the proposed strategy.Comment: 31 pages, 9 figures, submitted to Applied Energ
Control of sunroof buffeting noise by optimizing the flow field characteristics of a commercial vehicle
When a commercial vehicle is driving with the sunroof open, it is easy for the problem of sunroof buffeting noise to occur. This paper establishes the basis for the design of a commercial vehicle model that solves the problem of sunroof buffeting noise, which is based on computational fluid dynamics (CFD) numerical simulation technology. The large eddy simulation (LES) method was used to analyze the characteristics of the buffeting noise with different speed conditions while the sunroof was open. The simulation results showed that the small vortex generated in the cab forehead merges into a large vortex during the backward movement, and the turbulent vortex causes a resonance response in the cab cavity as the turbulent vortex moves above the sunroof and falls into the cab. Improving the flow field characteristics above the cab can reduce the sunroof buffeting noise. Focusing on the buffeting noise of commercial vehicles, it is proposed that the existing accessories, including sun visors and roof domes, are optimized to deal with the problem of sunroof buffeting noise. The sound pressure level of the sunroof buffeting noise was reduced by 6.7 dB after optimization. At the same time, the local pressure drag of the commercial vehicle was reduced, and the wind resistance coefficient was reduced by 1.55% compared to the original commercial vehicle. These results can be considered as relevant, with high potential applicability, within this field of researchThis work was supported by the National Natural Science Foundation of China (No. 52065013), the Guangxi Youth Science Fund Project (2018GXNSFBA281012), the Innovation-Driven Development Special Fund Project of Guangxi (Guike AA19182004), and the Liuzhou Scientific Research and Planning Development Project (2018AA20301)S
Research progress and prospects of urban resilience in the perspective of climate change
The natural hazards caused by climate change have a significant impact on the production and life of urban residents, enhancing urban resilience is an important way to cope with climate disasters and ensure the safety of urban systems. Based on the “urban resilience” research relevant literature, the paper applies bibliometric analysis software to reveal the research hotspots and evolution trends of urban resilience in the perspective of climate change. The results indicate that the main research contents can be summarized into four aspects: ⅰ) influencing factors of urban resilience; ii) evaluation index and method of urban resilience; iii) the impact of climate change on urban resilience; ⅳ) Enhancing urban resilience in response to climate change. Finally, potential directions for future research on urban resilience were proposed, multi-dimensional research on urban resilience should be carried out from aspects of theoretical development, urban planning based on resilience mechanisms should be carried out from the perspective of planning practice, and innovation and reform should be carried out in policy implementation and urban management. Accurately understanding the conceptual connotation and construction mechanism of urban resilience is a crucial premise for climate mitigation and adaptation. Relevant research conclusions can provide useful reference for theoretical research and spatial planning of resilient cities
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