Comparison of discrete and continuous travel time models for a multi-aisle AS/RS under different operating conditions

2021 ◽  
Vol 40 (1) ◽  
pp. 87
Author(s):  
Vishwesh Singbal ◽  
Gajendra Kumar Adil
Keyword(s):  
Travel Time ◽  
Operating Conditions

scholarly journals Operating Time Division for a Bus Route Based on the Recovery of GPS Data

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Jian Wang ◽  
Yang Cao
Keyword(s):  
Travel Time ◽  
Operating Time ◽  
Time Of Day ◽  
Operating Conditions ◽  
Gps Data ◽  
Recovery Method ◽  
Speed Up ◽  
Link Travel Time ◽  
Partition Method ◽  
Bus Travel Time

Bus travel time is an important source of data for time of day partition of the bus route. However, in practice, a bus driver may deliberately speed up or slow down on route so as to follow the predetermined timetable. The raw GPS data collected by the GPS device equipped on the bus, as a result, cannot reflect its real operating conditions. To address this concern, this study first develops a method to identify whether there is deliberate speed-up or slow-down movement of a bus. Building upon the relationships between the intersection delay, link travel time, and traffic flow, a recovery method is established for calculating the real bus travel time. Using the dwell time at each stop and the recovered travel time between each of them as the division indexes, a sequential clustering-based time of day partition method is proposed. The effectiveness of the developed method is demonstrated using the data of bus route 63 in Harbin, China. Results show that the partition method can help bus enterprises to design reasonable time of day intervals and significantly improve their level of service.

scholarly journals Distance and Travel Time Modeling in High-Level Picker-To-Part Systems (3-D Warehouses)

2019 ◽  
Vol 54 (6) ◽  
Author(s):  
Jose Alejandro Cano ◽  
Alexander Correa-Espinal ◽  
Rodrigo Andrés Gómez-Montoya ◽  
Pablo Cortés
Keyword(s):  
Statistical Analysis ◽  
Experimental Design ◽  
Travel Time ◽  
Operating Conditions ◽  
Research Proposal ◽  
Objective Functions ◽  
Reference Levels ◽  
Routing Problem ◽  
Time Modeling ◽  
High Level

This article describes new minimum travel time formulations for the picker routing problem (PRP) in 3-D warehouses based on real operating conditions, such as height reference levels, to leave aisles and to pick devices with simultaneous and sequential movements. This study validated the proposed formulations through an experimental design, statistical analysis based on ANOVA, and comparison of means. This research proposal allows for improving order picking models for 3-D warehouses by including appropriate travel time formulations related to vertical and horizontal movements and height reference levels to leave aisles, which affect the objective functions involving travel time.

Implementation of Bus Priority with Queue Jump Lane and Pre-Signal at Urban Intersections with Mixed Traffic Operations: Lessons Learned?

2019 ◽  
Vol 2673 (3) ◽  
pp. 646-657 ◽  
Author(s):  
Kinjal Bhattacharyya ◽  
Bhargab Maitra ◽  
Manfred Boltze
Keyword(s):  
Travel Time ◽  
Lessons Learned ◽  
Operating Conditions ◽  
Mixed Traffic ◽  
Urban Centers ◽  
Bus Priority ◽  
The Road ◽  
The Social ◽  
Road Space ◽  
Travel Time Savings

In mixed traffic streams, especially near the intersections, buses suffer significantly due to congestion and excessive delays compared with other modes as they operate on fixed routes. To increase the attractiveness of bus journeys by improving schedule-reliability and reducing journey times, it is necessary to give priority to buses by segregating them from the main traffic stream. However, the road space is generally constrained in the cities and dedicated bus lanes are not a feasible solution in the majority of urban centers. This paper aims to investigate the effectiveness of queue jump lanes (QJL) with and without pre-signal for non-priority traffic. The impacts on traffic and bus operations are analyzed based on implementations at two signalized approaches with distinct traffic and roadway characteristics in the Kolkata city, India. The field implementation indicated travel time savings to passengers as a whole with variations with respect to different scenarios. Impacts on travel time and vehicle discharge yielded the effective benefits of the bus priority implementation. It was also meaningful and interesting to investigate the impacts on driver behavior in terms of bus stop manuevres, and the social acceptability of such implementation. The changes in safety-related aspects and driver violations are some of the aspects which could not be directly investigated in an analytical or micro-simulation platform, but needed a field implementation. The experiences gained from the field implementation of bus priority with QJL are expected to encourage practitioners to apply similar treatments in other cities in emerging countries with analogous operating conditions.

Cathodoluminescence of Catalyst Crystallites

1982 ◽  
Vol 40 ◽  
pp. 664-665
Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
D.B. Darby ◽  
C. Warwick
Keyword(s):  
Defect Density ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Semiconductor Materials ◽  
Environmental Cell ◽  
High Resolution Structure ◽  
Commercially Important ◽  
Crystallographic Defects ◽  
Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

1994 ◽  
Vol 52 ◽  
pp. 412-413
Author(s):  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Damage ◽  
Low Dose ◽  
Dynamic Range ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Digital Data ◽  
Ccd Cameras ◽  
Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

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