Effect of change of sand properties on travel distance of ricocheted debris

The debris from exploded buildings can ricochet after colliding with the ground,thus increasing the debris travel distance and danger from any associated impacts or collisions.To reduce this danger,the travel distance of ricocheted debris must be accurately predicted.This study analyzed the change in the travel distance of ricocheted concrete debris relative to changes in the properties of a sand medium.Direct shear tests were conducted to measure the change in internal friction angle as a function of temperature and water content of the sand.Finite element analysis(FEA)was then applied to these variables to predict the speed and angle of the debris after ricochet.The FEA results were compared with results of low-speed ricochet experiments,which employed variable temperature and water content.The travel distance of the debris was calculated using MATLAB,via trajectory equations considering the drag coefficient.As the internal friction angle decreased,the shear stress decreased,leading to deeper penetration of the debris into the sand.As the loss of kinetic energy increased,the velocity and travel distance of the ricocheted debris decreased.Changes in the ricochet velocity and travel distance of the debris,according to changes in the internal friction angle,indicated that the debris was affected by the environment.

On the Association between Travel Distance and Treatment Choice for Low-Risk Prostate Cancer: Results from a Rural State

Background: Evidence suggests that cancer patients with increased travel burden to treatment centers may have limited treatment options. Purpose: To investigate the association between travel distance to a treatment facility and initial treatment choice among young men with low-risk prostate cancer in a rural state. Methods: A retrospective medical charts review was conducted of young men (65 years or younger) newly diagnosed with low-risk prostate cancer from January 1, 2005 through December 31, 2014 who were treated with either active surveillance, radical prostatectomy, or brachytherapy at either of the two major hospital systems in Bismarck, ND, USA. Results: Information on a random sample of 242 patients was studied. The majority of patients (66%) received radical prostatectomy. Patients who received radical prostatectomy were significantly younger (p-value 0.001). PSA at diagnosis, clinical stage, and Gleason score were not associated with treatment choice (p-value = 0.06;p-value = 0.1794;and p-value = 1.00;respectively). Adjusting for age at diagnosis, PSA at diagnosis, and treatment facility, treatment choice was not associated with travel distance (p-value = 0.309). Patients treated at St. Alexius facility were more likely to undergo radical prostatectomy than Sanford health patients (p-value Conclusions: We found no association between travel distance and treatment choice for low-risk prostate cancer. Treatment choice was associated with institution which may suggest institutional bias in patterns of care.

Spatial Structure of Urban Residents’ Leisure Activities: A Case Study of Shenyang, China

The spatial characteristics of residents’ leisure activities not only reflect their demand for urban leisure space but also affect the urban spatial layout. This study takes Shenyang, China as an example and analyzes the characteristics of residents’ leisure activities through questionnaires. On this basis, it uses point of interest data and mobile phone signaling data to identify various types of residential and leisure functional relationships, and uses spatial analysis and community detection to assess the distance characteristics, flow patterns, and community structure of residents’ leisure activities, so as to discuss the spatial structure of residents’ leisure activities in Shenyang. The results showed that: (1) in addition to leisure at home, Shenyang residents mainly went to shopping malls, supermarkets,and parks for leisure activities, and the proportions of residents of the two types of leisure activities were approximately equal;(2) the average distances that residents traveled for shopping and park leisure were near in the middle and far in the periphery, and the travel costs of peripheral residents for centrally located leisure were higher than those for residents in central areas;(3) the flow patterns of the residential-shopping and residential-park functional relationships displayed clustering mode characteristics, and Shenyang presented a significant monocentric structure;and (4) residents’ shopping activities were concentrated in the southern community, and walking in the park activities were concentrated in the western community. Residents’ leisure activities were characterized by centripetal agglomeration,which was prone to problems such as traffic congestion and big city diseases. The spatial expansion process in the city was characterized by obvious directional inheritance and path dependence, and the construction of sub-cities is needed to improve the related service facilities.

The Road Traffic Analysis Based on an Urban Traffic Model of the Circular Working Field

Under a relatively realistic model, this paper theoretically analyzes the road traffic status inside an urban working field, including its radial roads and circular ones. Concretely, the radial and the circular average traveling distances of a car commuter in a tiny ring with wide dx are first derived, and then the necessary road area, road area rate distributions, the proportion between the radial and the circular roads to be needed are also calculated. The results presented here and the properties shown through the numerical analysis are considered to be significant at the very beginning stage of designing an urban city.