oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 184 )

2018 ( 1078 )

2017 ( 998 )

2016 ( 1038 )

Custom range...

Search Results: 1 - 10 of 23140 matches for " LIVE HIGH-TRAIN LOW "
All listed articles are free for downloading (OA Articles)
Page 1 /23140
Display every page Item
Application of altitude/hypoxic training by elite athletes
RANDALL L. WILBER
Journal of Human Sport and Exercise , 2011,
Abstract: At the Olympic level, differences in performance are typically less than 0.5%. This helps explain why many contemporary elite endurance athletes in summer and winter sport incorporate some form of altitude/hypoxic training within their year-round training plan, believing that it will provide the “competitive edge” to succeed at the Olympic level. The purpose of this paper is to describe the practical application of altitude/hypoxic training as utilized by elite athletes. Within the general framework of the paper, both anecdotal and scientific evidence will be presented relative to the efficacy of several contemporary altitude/hypoxic training models and devices currently used by Olympic-level athletes for the purpose of legally enhancing performance. These include the three primary altitude/hypoxic training models: 1) live high + train high (LH + TH), 2) live high + train low (LH + TL), and 3) live low + train high (LL + TH). The LH + TL model will be examined in detail and will include its various modifications: natural/terrestrial altitude, simulated altitude via nitrogen dilution or oxygen filtration, and normobaric normoxia via supplemental oxygen. A somewhat opposite approach to LH + TL is the altitude/hypoxic training strategy of LL + TH, and data regarding its efficacy will be presented. Recently, several of these altitude/hypoxic training strategies and devices underwent critical review by the World Anti-Doping Agency (WADA) for the purpose of potentially banning them as illegal performance-enhancing substances/methods. This paper will conclude with an update on the most recent statement from WADA regarding the use of simulated altitude devices.
Multiuser Receiver Scheme with SIC for PUCCH in High Speed Train Environment  [PDF]
Wei Wang, Guangliang Ren
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.53B2057
Abstract: A multiuser receiver scheme with successive interference cancellation (SIC) is proposed to suppress multiuser interference for physical uplink control channel (PUCCH) in high speed train (HST) environment. In the proposed algorithm, each user’s signal is detected iteratively in a descending order according to the signal strength at eNB. During each iteration, the strongest signal of all users’ is detected and regenerated, and then is subtracted from the composite signal before decoding the next user. Simulation results show that the proposed scheme obtains remarkable gains, e.g. 2 dB for PUCCH format 2 with 3 users in HST scenario 1. The improvement is more pronounced in the case of increasing number of users, e.g. 3.3 dB with 6 users.
Minimum Curve Radii for High-Speed Trains, Including the Gyroscopic Moments of the Wheels  [PDF]
Ronald L. Huston
World Journal of Engineering and Technology (WJET) , 2017, DOI: 10.4236/wjet.2017.51010
Abstract: This paper studies the title problem including an analysis of the gyroscopic effects of the wheels of a rail-car travelling at high-speed around a level, horizontal curve. The analysis is based upon the fundamental principles of dynamics. The result is a design formula for the minimum curve radius needed to prevent derailment. Aside from the rail car geometric and physical properties, the minimum curve radius depends upon the square the train speed. An illustrative example shows that the wheel gyroscopic effect is destabilizing and additive to the centrifugal force derailment tendency. From a track design perspective, however, the gyroscopic effect is relatively small compared with the centrifugal force effect.
高海拔地区高速铁路隧道空气动力学特性
Aerodynamic Effect Induced by High-Speed Train Entering into Tunnel in High Altitude Area

骆建军
- , 2016, DOI: 10.3969/j.issn.0258-2724.2016.04.002
Abstract: 为了获得高海拔地区隧道空气动力学效应随海拔高度的变化规律,针对我国中西部及西南部艰险困难山区高海拔低温的气候特点,给出了高速列车进入隧道时产生压缩波的三维可压缩、粘性、非定常流场数值模拟方法,对高速列车进入低气压隧道时产生的气动效应进行研究.研究结果表明隧道所处海拔高度的变化对隧道内压缩波及隧道出口微气压波的影响较大,随着海拔的升高,大气压的降低会导致隧道内压缩波及隧道出口微气压波的最大值及最小值呈线性降低,降低幅度分别为70%和71%,而大气压的变化对测点压力波形无影响;随着温度的降低,隧道内的压缩波及隧道出口微气压波的最大值及最小值均降低,降低幅度分别为34%和36%,基本呈线性效应;海拔高度的变化对隧道内及隧道外气动效应的影响比温度的大.针对我国高海拔地区的气候特点,根据旅客的舒适度准侧,提出了CRH380B型高寒列车在列车速度为350 km/h、气压为75.99 kPa及气体温度为250 K时的隧道净空断面积约为96 m2,可为下一步高海拔低温条件下高速铁路隧道净空断面积的设计提供参考.
: According to high altitude and low temperature climate conditions of midwestern and southwestern dangerous regions of China, a numerical simulation method of three dimensional compressible, viscous and unsteady compression waves induced by a high-speed train entering a tunnel was presented and aerodynamic effect also be studied.The results show that the range of the tunnel altitude has a profound effect on compression waves inside the tunel and micro-pressure waves at the tunnel exit. With the increase of altitude, the decrease of atmospheric pressure will cause a linear decrease of maximum and minimum value of compression waves and micro-pressure waves by 34% and 36% respectively, and has little influence on wave forms at measuring points.Besides, as temperature decreasing, the maximum and minimum value of compression waves and micro-pressure waves decrease linearly by 34% and 36% respectively.According to comparison, it assumes that altitude plays a much larger role in aerodynamic effect outside or inside the tunnel than temperature. At last, according to high altitude climate conditions of China and the principle that aims to make passengers comfortable, it provides that the tunnel area is 96 m2 when the CRH380B train runs at 350 km/h, 75.99 kPa and 250 K. This suggestion provides a guidance for sectional area designing of high-speed railway tunnel in high altitude and low temperature conditions
低温环境下高速列车车内噪声问题及控制方案
Interior Noise Issues and Noise Control Measures of High-Speed Train in Low Temperature

孙强,张捷,肖新标,王金田,滕万秀,高阳
- , 2018, DOI: 10.16450/j.cnki.issn.1004-6801.2018.06.021
Abstract: 对低温环境下(-30℃)的250 km/h高速列车车内客室端部噪声进行测试,深入分析了运行环境温度对车内噪声的影响。通过对比夏季、冬季两种季节因素,掌握了不同环境下高速列车的车内振动噪声特性、车下声源特性和声振传递路径,研究了低温环境下的高速列车减振降噪技术,以提高低温环境下高速列车的车内噪声性能。研究结果表明,车内客室端部噪声异常问题是由于受到列车250 km/h匀速运行时的过枕垮频率激励,而冬季运行时转向架区域减振性能下降,使得该频率更容易传递至车内所致,并激发车内客室空腔的声学模态。通过从传递路径上进行控制,使用一种金属减振器代替原有地板的支撑结构,优化车体内地板和外地板之间的弹性支撑,能够有效改善低温环境下高速列车车内客室端部异常噪声问题。
The interior noise at the coach end of a high-speed train running at 250 km/h in the low temperature environment (-30℃) is measured, and the effect of the temperature on the interior noise is analysed. By comparing the different seasons of summer and winter, the influences of different temperatures on the interior noise and vibration, bogie area vibration and their relationships are obtained. The technology of noise and vibration control in low temperature is studied in order to improve the noise performance of high-speed trains. The results show that: the abnormal interior noise at the coach end is caused by the excitation of sleeper passing frequency when the train is running at 250 km/h. In winter, the damping performance in bogie area decreases, so that the sleeper passing frequency is easier to transfer into the interior. Moreover, this structural vibration propagation further stimulated the acoustic modal of the cavity. Focus on the sound transfer paths and optimizing the connection between the interior floor and the exterior floor by using a metal damper to replace the original one, so that the abnormal interior noise at the coach end in low temperature can be effectively improved.
Dynamic Response Analysis of High-Speed Train Gearbox Housing Based on Equivalent Acceleration Amplitude Method  [PDF]
Xiqiao Li, Xi Wang, Chang Xu, Guangquan Li
World Journal of Engineering and Technology (WJET) , 2017, DOI: 10.4236/wjet.2017.52020
Abstract: Gearbox, as the crucial transmission equipment of high-speed train drive system, bears mainly the impact of wheel-rail excitation during its application, resulting in fatigue failure of the housing structure. In order to analyze the vibration characteristics of the high-speed train gearbox housing, a test had been performed under operating condition on Wuhan-Guangzhou High-Speed Railway, where a host of vibration characteristics of different parts of housing had been obtained, and vibration signals had also been comparatively analyzed using acceleration amplitude spectrum and equivalent acceleration amplitude method. The result showed that the vibration level of the measuring point A on the joint part of the gearbox housing and axle bearing block was higher than that of the measuring point B on the upper part of the gearbox housing, both horizontally and vertically. And there existed attenuation during the transmission process of vibration from point A to Point B. Further, when a train was moving at a high speed, the gearbox vibration at the head carriage was better than that at the tail carriage. In addition, when a train slowed down from 300 km/h to 200 km/h, the horizontal equivalent acceleration amplitude dropped by 58% while the vertical one declined by 62%. Equivalent acceleration amplitude method was used to identify the vibration relations among different parts of housing, and the validity and applicability of this method were verified by data analysis. The study provided reference to ensure the operating safety of high-speed train drive system and design of new housing structure.
Baixo peso ao nascer no Brasil de acordo com as informa??es sobre nascidos vivos do Ministério da Saúde, 2005
Andrade, Carla Louren?o Tavares de;Szwarcwald, Celia Landmann;Castilho, Euclides Ayres de;
Cadernos de Saúde Pública , 2008, DOI: 10.1590/S0102-311X2008001100011
Abstract: although the brazilian information system on live births (sinasc) has expanded its coverage and improved its data quality since the system was implemented, the live birth count in brazil is still not complete. the current study analyzes inequalities in low birth weight in brazil in 2005, based on geographic factors, municipality of residence, maternal schooling, and prenatal care. an analysis of all live births showed a low birth weight paradox, namely high percentages in areas with the highest socioeconomic development. the main explanation for these paradoxical findings involves shorter neonatal survival and inadequate recording of premature births in poorer municipalities. considering at-term live births from non-multiple gestations, inequalities were found in maternal schooling. comprehensive, quality prenatal care could have a greater impact by reducing negative outcomes of gestation and decreasing the socioeconomic inequalities of perinatal health in brazil.
Impact of North-South Shift of Azores High on Summer Precipitation over North West Europe  [PDF]
Shahnaz Ali Rashid, Muhammad J. Iqbal, Muhammad A. Hussain
International Journal of Geosciences (IJG) , 2012, DOI: 10.4236/ijg.2012.325099
Abstract: Several Studies demonstrate that North Atlantic Oscillation (NAO) influences variability of climate over Europe. As NAO is has significant influence on climate of Europe during boreal cold season (November to April), we use the centers of action approach for the study of summer precipitation (June to August) variability over Europe, taking into account variations in the components of the NAO North Atlantic Oscillation (NAO), the Azores High and the Icelandic Low pressure systems. This study shows that north-south shifts of the Azores High has significant impact on interannual variations of summer precipitation over North West Europe, there being more precipitation when the Azores High shifts southward versus when it is northward. Thus this article demonstrate that when the Azores High system is to the south there is flux of moist and warm air from the Atlantic into NW Europe. We present a regression model for summer precipitation over North-west in which the Azores High latitude and the Icelandic low longitude are independent variables and it explains 53 percent of the variance of precipitation during 1952-2002, a significant enhancement over the NAO value of R2 = 0.10.
Walnut Trim down Lipid Profile and BMI in Obese Male in Different Ethnic Groups of Quetta Population, Pakistan  [PDF]
Rehana Mushtaq, Rubina Mushtaq, Sobia Khwaja, Zahida Tasawar Khan
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.410139
Abstract:

A total of 64 male obese subjects were randomized to observe the effect of 40 g of walnut in daily breakfast on lipid profile and Body Mass Index (BMI), total Cholesterol (CHO), Triglyceride (TG) High Density Lipoprotein (HDL) cholesterol and Low Density Lipoprotein (LDL) cholesterol in obese male subjects of various ethnics i.e. Baloch (B), Pathan (P), Hazara (H) and Punjabi (PU) residing in Quetta region of Balochistan for this purpose four weeks controlled study was designed. A batch of 32 obese male subjects 8 from each ethnic group as a control and another batch of 32 obese males 8 from each ethnic group as treated were selected. Twelve hour fasting blood samples a day after stoppage of walnut were taken from obese control and obese treated subjects. Daily walnut consumption in obese male subjects evidently demonstrated reduced BMI in all ethnic groups. Walnut supplementation in obese exhibited significant reduction in cholesterol level in Baloch (P < 0.001) and Punjabi (P < 0.01) males. There was profound and statistically significant [B (P < 0.05), P (P < 0.05), H (P < 0.01) and PU (P < 0.05)] elevation in HDL-C in all male ethnic groups. In male sub-population LDL-C was significantly [P (P < 0.01), H (P < 0.001) and PU (P < 0.05)] reduced in these groups. In these subjects walnut supplementation showed pronounced reduction [B (P < 0.001), P (P < 0.05), H (P < 0.001) and PU (P < 0.001)] in triglyceride levels. The constructive influence of walnut on lipid profile suggests that walnut rich diet may have advantageous effects beyond changes in plasma lipid level.

Idiopathic Reactive Hypoglycemia: Mechanisms of Onset and Remission with High Protein Low Carbohydrate Diet  [PDF]
Keshavan Prakash, Mary Kabadi, Udaya M. Kabadi
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2015, DOI: 10.4236/ojemd.2015.59015
Abstract: Objective: Idiopathic reactive hypoglycemia is defined as early postprandial hypoglycemia occurring on ingestion of high carbohydrate containing meal. Remission ensues with high protein low carbohydrate diet. This study assessed roles of insulin and glucagon in its onset and remission. Methods: Plasma glucose, insulin and glucagon were determined after an overnight fast and repeatedly until 180 minutes on ingestion of 3 meals; 100 g glucose; 100 g pure protein liquid and mixture of 50 g each at 14 days’ interval. Five adults with IRH and 6 age matched healthy volunteers participated. Results: In IRH, glucose ingestion induced prompt rise in glucose (5.1 ± 0.8 to10.5 ± 1.2 mM/L) followed later by hypoglycemia (2.6 ± 0.4 mM/L). Insulin rose from 7 ± 2 to 90 ± 18 mU/L. Glucagon rose initially (10% ± 2%) from elevated basal concentration (373 ± 57 mU/L) followed by later decline (-43% ± 12%). On protein ingestion, glucose declined followed by a restoration to basal level while both insulin and glucagon rose (28 ± 6 mU/L; 148% ± 38%, p < 0.01). However, insulin response was lower and glucagon rise was greater when compared to responses on glucose ingestion (p < 0.01). With mixed meal, glucose (8.2 ± 0.6 mM/L), insulin (65 ± 12 mU/L) and glucagon (48% ± 7%) responses were lesser than rises following glucose ingestion (p < 0.05) and hypoglycemia did not occur. Conclusion: In IRH, initial hyperglycemia on glucose ingestion may be exacerbated by paradoxical glucagon rise and hypoglycemia may be induced by increased insulin and declining glucagon responses. Resolution of hypoglycemia with high protein low carbohydrate diet may be attributed to blunting of insulin response and concurrent glucagon rise.
Page 1 /23140
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.