16,379 research outputs found
Optimal Storage Rack Design for a 3-dimensional Compact AS/RS
Full text linkIn this paper, we consider a newly-designed compact three-dimensional automated storage and retrieval system (AS/RS). The system consists of an automated crane taking care of movements in the horizontal and vertical direction. A gravity conveying mechanism takes care of the depth movement. Our research objective is to analyze the system performance and optimally dimension of the system. We estimate the crane’s expected travel time for single-command cycles. From the expected travel time, we calculate the optimal ratio between three dimensions that minimizes the travel time for a random storage strategy. In addition, we derive an approximate closed-form travel time expression for dual command cycles. Finally, we illustrate the findings of the study by a practical example.AS/RS;Warehousing;Order Picking;Travel Time Model;Compact Storage Rack Design
Optimal Storage Rack Design for a 3D Compact AS/RS with Full Turnover-Based Storage
Full text linkCompact, multi-deep (3D) automated storage and retrieval systems (AS/RS) are becoming increasingly popular for storing products with relatively low turnover on a compact area. An automated storage/retrieval crane takes care of movements in the horizontal and vertical direction in the rack, and a gravity conveying mechanism takes care of the depth movement. An important question is how to layout such systems to minimize the product storage and retrieval times. Although much attention has been paid to 2D AS/RS, multi-deep systems have hardly been studied. This paper studies the impact of system layout on crane travel time. We calculate the rack dimensions that minimize single-command cycle time under the full-turnover-based storage policy. We prove the expected travel time is minimized when the rack is square-in-time in horizontal and vertical directions and the conveyor’s dimension is the longest. We compare the model’s results with the performance of the random storage policy and show a significant crane travel time reduction can be obtained. We illustrate the findings of the study by applying them in a practical example.AS/RS;Warehousing;Order Picking;Storage Rack Design;Travel Time Model;Turnover-Based Storage
Juraserphus Zheng & Chen 2017, gen. nov.
No full textJuraserphus gen. nov. urn:lsid:zoobank.org:act:38CDA49B-F168-47B0-9CFD-97EE52F82733 Type species Juraserphus modicus gen. et sp. nov., designated herein. Diagnosis Forewing 1-Rs as long as 1-M; 1-M more than twice as long as 1m-cu; 2r-rs arising from middle of pterostigma, its width more than twice as long as width of pterostigma; 1cu-a antefurcal, 2cu-a antefurcal; forking of Rs+M located approximately one-third of distance bewteen 1m-cu and 2r-rs, closer to 1m-cu; cell 1mcu complete trapezoid and less than half of cua. Hind wing with cells r and rm closed. Metasoma spindle-shaped, with elongated segments. Short ovipositor, only extending slightly beyond metasomal apex. Etymology The generic name is composed of the prefix ‘Jura’ from the Jurassic period and the suffix of the genus name ‘serphus’. The gender is masculine. Species included Type species only.Published as part of Zheng, Yan & Chen, Jun, 2017, A new mesoserphid wasp from the Middle Jurassic of northeastern China (Hymenoptera, Proctotrupoidea), pp. 1-8 in European Journal of Taxonomy 379 on pages 2-3, DOI: 10.5852/ejt.2017.379, http://zenodo.org/record/111916
Optimal Zone Boundaries for Two-class-based Compact 3D AS/RS
Full text linkCompact, multi-deep (3D), Automated Storage and Retrieval Systems (AS/RS) are becoming more common, due to new technologies, lower investment costs, time efficiency and compact size. Decision-making research on these systems is still in its infancy. We study a particular compact system with rotating conveyors for the depth movement and a Storage/Retrieval (S/R) machine for the horizontal and vertical movement of unit loads. We determine the optimal storage zone boundaries for such systems with two product classes: high and low turnover, by minimizing the expected Storage/Retrieval (S/R) machine travel time. We propose a mixed-integer nonlinear programming model to determine the zone boundaries. A decomposition algorithm and a one dimensional search scheme are developed to solve the model. The algorithm is complex, but the results are appealing since most of them are in closed-form and easy to apply to optimally layout the 3D AS/RS rack. The results are compared with those under random storage, and show that a significant reduction of the machine travel time can be obtained. Finally, a practical example is studied to demonstrate the use and validate our findings.AS/RS;Class-based storage;Order picking;Storage rack design;Travel time model
Risk Factors in Motorcyclist Fatalities in Taiwan
No full text[[abstract]]Objective: To assess the impact of the following factors on rider fatality: rider's age, gender, licensing status, accident liability, use of helmet, alcohol consumption, vehicle class, road conditions, presence of passengers, and passenger injuries. Methods: Data on motorcycle accidents in Taiwan between 2006 and 2008 were analyzed. A logistic regression model was used to establish a fatality risk model for motorcyclists and investigate high-risk factors for motorcyclist fatality. Results: Higher fatality rates among motorcycle riders correlate with the following factors: male, older, unlicensed, not wearing a helmet, riding after drinking, and driving heavy (i.e., above 550 cc) motorcycles. In addition, motorcyclists involved in nighttime, nonurban single-vehicle accidents have a higher risk of death, and lone riders have a higher risk of death in accidents than do riders carrying passengers. The seriousness of passenger injury also correlates positively with the rider's risk of death. Conclusions: Nearly 60 percent of all driving fatalities in Taiwan involve motorcycles. Consideration of factors behind the high frequency and risk of motorcycle deaths, specifically rider age above 60 years, not wearing a motorcycle helmet, riding after drinking, and driving without a valid license, could help in the development of effective traffic safety management measures.[[note]]SC
astromatt42/digb_sfgs: Release for 10.21203/rs.3.rs-106679/v1
No full textThis release was used to compute the results in https://doi.org/10.21203/rs.3.rs-106679/v1
For any queries please contact the corresponding author
RS-U-Net.
No full textReverberation is the primary background interference of active sonar systems in shallow water environments, affecting target position detection accuracy. Reverberation suppression is a signal processing technique used to improve the clarity and accuracy of echo by eliminating the echoes, reverberations, and noise that occur during underwater propagation.This paper proposes an end-to-end network structure called the Reverberation Suppression Network (RS-U-Net) to suppress the reverberation of underwater echo signals. The proposed method effectively improves the signal-to-reverberation ratio (SRR) of the echo signal, outperforming existing methods in the literature. The RS-U-Net architecture uses sonar echo signal data as input, and a one-dimensional convolutional network (1D-CNN) is used in the network to train and extract signal features to learn the main features. The algorithm’s effectiveness is verified by the pool experiment echo data, which shows that the filter can improve the detection of echo signals by about 10 dB. The weights of reverberation suppression tasks are initialized with an auto-encoder, which effectively uses the training time and improves performance. By comparing with the experimental pool data, it is found that the proposed method can improve the reverberation suppression by about 2 dB compared with other excellent methods.</div
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