scholarly journals How to Choose “Last Mile” Delivery Modes for E-Fulfillment

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Xuping Wang ◽  
Linmin Zhan ◽  
Junhu Ruan ◽  
Jun Zhang
Keyword(s):  
Population Density ◽  
High Population ◽  
High Population Density ◽  
Order Quantity ◽  
Advantages And Disadvantages ◽  
Delivery Modes ◽  
Last Mile ◽  
Fresh Vegetables ◽  
The Cost ◽  
Last Mile Delivery

“Last mile” delivery has become one of the bottlenecks of e-logistics. This paper aims to explore the competitiveness of three “Last mile” delivery modes—attended home delivery (AHD), reception box (RB), and collection-and-delivery points (CDPs) in different scenarios, especially in high population density scenario. The advantages and disadvantages of each mode are introduced first. Then each mode’s operation efficiency is solved with different kinds of vehicle routing problem (VRP) models and genetic algorithm (GA). Finally the cost of each mode is calculated on the basis of cost structures and operation efficiencies. The results show that different modes are suitable for different scenarios: (i) AHD and independent reception box work better in a scenario with sparse population or small order quantity; (ii) shared reception box and CDPs are more appropriate in the scenario with high population density and large order quantity, and the better one depends on the cost of labors and facilities; (iii) RB is desirable in some circumstances as delivering fresh vegetables and fruits to the ones living in high-grade communities.

Hybrid last mile delivery fleets with crowdsourcing: A systems view of managing the cost‐service trade‐off

2021 ◽  
Author(s):  
Vincent E. Castillo ◽  
John E. Bell ◽  
Diane A. Mollenkopf ◽  
Theodore P. Stank
Keyword(s):  
Service Trade ◽  
Trade Off ◽  
Last Mile ◽  
The Cost ◽  
Last Mile Delivery ◽  
Systems View

scholarly journals Recruitment sex ratios in gray-tailed voles (Microtus canicaudus) in response to density, sex ratio, and season

2003 ◽  
Vol 81 (8) ◽  
pp. 1306-1311 ◽  
Author(s):  
Monica L Bond ◽  
Jerry O Wolff ◽  
Sven Krackow
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Resource Competition ◽  
Sex Ratios ◽  
Female Offspring ◽  
High Population ◽  
Reproductive Value ◽  
High Population Density ◽  
Adult Sex Ratio ◽  
Sex Ratio Adjustment

We tested predictions associated with three widely used hypotheses for facultative sex-ratio adjustment of vertebrates using eight enclosed populations of gray-tailed voles, Microtus canicaudus. These were (i) the population sex ratio hypothesis, which predicts that recruitment sex ratios should oppose adult sex-ratio skews, (ii) the local resource competition hypothesis, which predicts female-biased recruitment at low adult population density and male-biased recruitment at high population density, and (iii) the first cohort advantage hypothesis, which predicts that recruitment sex ratios should be female biased in the spring and male biased in the autumn. We monitored naturally increasing population densities with approximately equal adult sex ratios through the spring and summer and manipulated adult sex ratios in the autumn and measured subsequent sex ratios of recruits. We did not observe any significant sex-ratio adjustment in response to adult sex ratio or high population density; we did detect an influence of time within the breeding season, with more female offspring observed in the spring and more male offspring observed in the autumn. Significant seasonal increases in recruitment sex ratios indicate the capacity of female gray-tailed voles to manipulate their offspring sex ratios and suggest seasonal variation in the relative reproductive value of male and female offspring to be a regular phenomenon.

Aggregations of masked shrews ( Sorex cinereus ): density-related mating behavior? / Agrégation de musaraignes masquées ( Sorex cinereus ): accouplement relatif à la densité de la population?

Mammalia ◽  
2006 ◽  
Vol 70 (1-2) ◽  
Author(s):  
Thomas J. Maier ◽  
Katherine L. Doyle
Keyword(s):  
Population Density ◽  
Mating Behavior ◽  
High Population ◽  
High Population Density ◽  
Genetic Analyses ◽  
Highly Active ◽  
Sorex Cinereus

AbstractLarge aggregations of shrews have been reported and various explanations offered for this seemingly rare behavior; however, there has been little evidence to support any particular interpretation. We observed two small aggregations of highly active vocalizing Sorex cinereus while performing wildlife surveys in forested habitats in central Massachusetts, USA. These observations, in conjunction with a review of other reports, including genetic analyses, strongly suggest that such aggregations of adult Sorex are associated with mating behavior, more readily observed during periods of high population density. Published accounts of such behavior may be rare because primarily large aggregations have been reported; however, smaller breeding aggregations may be common.

Analysis of steroid hormone levels in female mice at high population density

1998 ◽  
Vol 64 (4) ◽  
pp. 529-533 ◽  
Author(s):  
John C Chapman ◽  
John J Christian ◽  
Mary Ann Pawlikowski ◽  
Sandra D Michael
Keyword(s):  
Population Density ◽  
Steroid Hormone ◽  
High Population ◽  
High Population Density ◽  
Hormone Levels ◽  
Female Mice

Environmental Issues Regarding Space Launches over the Black Sea

2013 ◽  
Vol 330 ◽  
pp. 805-810
Author(s):  
Dragos R. Rugescu
Keyword(s):  
Population Density ◽  
Black Sea ◽  
Environmental Issues ◽  
High Population ◽  
The Black Sea ◽  
Western Coast ◽  
High Population Density ◽  
Research Activity ◽  
The West ◽  
Space Project

The Romanian NERVA space project, aimed at building and using a small rocket launcher for injecting nanosatellites into a LEO, requires the establishment of a secure launching area. The first candidate is on the western coast of the Black Sea and the candidate launching and flight corridor is the west-east vector above the sea. A series of ecological and safety challenges appear due to the high population density of the regions close to the sea-shores of the Black Sea; they must be catalogued and securely solved, before any space activity above the Black Sea begins. The main challenges of such an endeavor are analyzed henceforth and several solutions that fall within the scope of a recent research activity of the NERVA team are proposed.

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