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1.
《Operations Research Letters》2022,50(1):50-56
We address a novel truck scheduling problem arising in crossdocking logistics, in which inbound trucks carry items (pallets) which must be sorted and loaded onto outbound trucks. We minimize the utilisation of the warehouse by focusing on the synchronisation between the different related trucks. The problem is to assign the trucks to the doors of the warehouse and sequence them, in order to minimize the total time spent in the system by the pallets. We discuss the complexity of the problem, showing that even with a single door the problem is NP-hard in general, and discuss some special cases. 相似文献
2.
光纤布拉格光栅热式流量传感器目前只适用于气体流量,为扩大其应用领域,设计了一种可用于液体流量测量的新型光纤布拉格光栅热式流量传感器。该光纤布拉格光栅热式流量传感器使用陶瓷加热片以恒定功率提供热量,不同流量的液体经过传感器时带走的热量不同,通过检测光纤布拉格光栅中心波长的变化就可以测得传感器的温度变化,进而推导出液体流量大小。通过温度传感测试实验和流量传感测试实验,验证了所设计的传感器可用于液体流量测量。实验结果表明,该传感器的流量测量范围为40.575~550.664 L/h。 相似文献
3.
Serrated jet nozzles are considered to be an efficient and practical passive control approach for jet noise. However, some fundamental mechanisms of serration effects on jet noise are not fully understood, especially in terms of the sound source. In this paper, a high-fidelity simulation framework using large-eddy simulation (LES) is demonstrated to predict near-field turbulence and far-field acoustics from an ultra-high-bypass-ratio engine with round and serrated nozzles. Far-field sound is predicted using Ffowcs Willams–Hawkings (FWH) integration. The results show that the serrated nozzle increases mixing near the nozzle and hence the turbulence decay rate, reducing the turbulence level downstream. The serrations shift the energy from the low frequencies to the high frequencies and decrease overall sound pressure levels by about 3 dB over the low-frequency range. Sound sources are analysed based on fourth-order space–time correlations. There are six major source components (, , , , , and ) inside the jet shear layers. The serrations are able to reduce the amplitude of these source terms, causing them to decay rapidly to a level below the round nozzle jet within 2D downstream of the nozzle. 相似文献
4.
Anna Nme
kov‐Makrlíkov Frank‐Michael Matysik Tom Navrtil Jií Barek Vlastimil Vysko
il 《Electroanalysis》2019,31(2):303-308
Flow injection analysis with amperometric detection (FIA‐AD) at screen‐printed carbon electrodes (SPCEs) in optimum medium of Britton‐Robinson buffer (0.04 mol ? L?1, pH 2.0) was used for the determination of three tumor biomarkers (homovanillic acid (HVA), vanillylmandelic acid (VMA), and 5‐hydroxyindole‐3‐acetic acid (5‐HIAA)). Dependences of the peak current on the concentration of biomarkers were linear in the whole tested concentration range from 0.05 to 100 μmol ? L?1, with limits of detection (LODs) of 0.065 μmol ? L?1 for HVA, 0.053 μmol ? L?1 for VMA, and 0.033 μmol ? L?1 for 5‐HIAA (calculated from peak heights), and 0.024 μmol ? L?1 for HVA, 0.020 μmol ? L?1 for VMA, and 0.012 μmol ? L?1 for 5‐HIAA (calculated from peak areas), respectively. 相似文献
5.
A new kind of flow gating interface (FGI) has been designed for online connection of CE with flow‐through analytical techniques. The sample is injected into the separation capillary from a space from which the BGE was forced out by compressed air. A drop of sample solution with a volume of 75 nL is formed between the outlet of the delivery capillary supplying the solution from the flow‐through apparatus and the entrance to the CE capillary; the sample is hydrodynamically injected into the CE capillary from this drop. The sample is not mixed with the surrounding BGE solution during injection. The functioning of the proposed FGI is fully automated and the individual steps of the injection process are controlled by a computer. The injection sequence lasts several seconds and thus permits performance of rapid sequential analyses of the collected sample. FGI was tested for the separation of equimolar 50 μM mixture of the inorganic cations K+, Ba2+, Na+, Mg2+, and Li+ in 50 mM acetic acid/20 mM Tris (pH 4.5) as BGE. The obtained RSD values for the migration times varied in the range 0.7–1.0% and the values for the peak area were 0.7–1.4%; RSD were determined for ten repeated measurements. 相似文献
6.
Photo-controlled reversible-deactivation radical polymerization(photo-RDRP) has been investigated as a "green" and spatiotemporally controlling pathway for polymer synthesis. While the combination of photo-RDRP and flow chemistry has offered opportunities to increase light intensity and enable uniform light irradiation, problems associated with flow approaches still remain for photoflow-RDRP, which has hindered merging flow polymerization with other cutting-edge techniques. Herein, we summarize challenges and recent achievements in photoflow-RDRP including the development of(a) droplet/slug-flow to regulate residence time distribution,(b) mixing techniques to tailor polymer,(c) polymerization induced self-assembly, and(d) computer-aided synthesis. We hope this work will provide informative knowledge to people in related fields and stimulate novel ideas to promote polymer synthesis in both academia and industry. 相似文献
7.
The urge of developing modern alternatives regarding industrial production has led to the creation of novel techniques that help overcome critical disadvantages from traditional batch mechanochemistry. One promising strategy includes the merging of flow processes with mechanochemistry. Two technologies are herein highlighted: twin-screw extrusion (TSE) and Impact (induction) in Continuous flow HEated Mechanochemistry (I-CHEM) allowing not only the industrial production of polymers but also active pharmaceutical ingredients, synthesis of (nano)materials, and the obtention of high-added value products from biomass and wastes valorization. 相似文献
8.
提出一种采用子带二值加权累积的海洋环境噪声互相关函数(NCF)提取经验格林函数(EGF)方法。首先将每一快拍NCF在频域划分为多个子带,每个子带内根据“累积后提取的EGF信噪比增加”的准则,确定各快拍NCF的加权系数为0或1,将各子带的加权累积结果谱白化后在频域拼接,再反傅里叶变换得到时域EGF。子带二值加权累积方法实现了每一快拍NCF累积前的频率自动选择,相比于已有的原始累积方法与时域二值加权累积算法,可以有效提高从较宽频率带宽的海洋环境噪声中提取EGF的信噪比。海试实验数据验证了该方法的有效性与优越性。 相似文献
9.
智能变形、变色、变温、变谱技术发展趋势下,低特征目标加速实现与自然地物背景的特征融合,导致复杂自然背景环境下低散射、微反射、弱辐射目标的检测与评估愈发困难,特定场景下潜在威胁目标的检测方法快速决策与准确评估成为了难题。为了提升离散目标、伪装目标、弱小目标、异常目标等低特征目标与复杂自然背景环境融合场景下的多特征检测算法的选择效率及其检测准确度,提出了目标与背景环境融合度(FD)参数模型,并设计了植被伪装目标嵌入草地背景、植被伪装目标嵌入土壤背景、植被及水泥路伪装目标嵌入土壤背景以及植被、水泥路、土壤伪装目标分别嵌入草地、水泥路、土壤背景等4种不同波谱特征分布场景的模拟图像数据,以及信噪比为200,400与800的高斯白噪声分别加入场景一的3种不同级别噪声比例的模拟图像数据。通过综合目标波谱信息、背景波谱信息、数据噪声比例等多种因素的综合试验分析,开展了基于目标与环境FD模型的多特征检测算法适应性评估研究。结果表明,在标准差均小于0.08的条件下,MtACE,MtAMF,MtCEM,SumACE,SumAMF,SumCEM,WtaACE,WtaAMF,WtaCEM等9大经典多特征检测算法对于4种波谱分布场景检测结果的FD参数平均值分别为0.320 0,0.350 2,0.862 4,0.365 8,0.365 8,0.846 1,0.680 0,0.680 0和0.948 2;在标准差均小于0.07的条件下,9大经典多特征检测算法对于3种不同级别噪声比例数据检测结果的FD参数平均值分别为0.313 5,0.320 9,0.774 7,0.369 6,0.369 6,0.847 5,0.695 6,0.695 6和0.960 3。通过不同波谱分布场景及不同噪声级别条件下的检测与融合度评估试验分析,实现了多特征检测算法的适应性能排序,大幅提升复杂场景下多种低特征目标的检测效率。综合波谱与噪声因素,对于复杂场景下离散分布的低特征目标检测,9大经典多特征检测算法的优先级顺序为:MtACE>MtAMF>SumACE=SumAMF>>WtaACE=WtaAMF>MtCEM>SumCEM>WtaCEM。 相似文献
10.