Stations are often regarded as change engines--places where passengers have to change as quickly and efficiently as possible from one mode of transport to another. Underpinned by research, NS （Netherlands Railways） ...Stations are often regarded as change engines--places where passengers have to change as quickly and efficiently as possible from one mode of transport to another. Underpinned by research, NS （Netherlands Railways） currently takes the view that stations should be transformed into dynamic urban portals that not only facilitate a speedy transfer but also make the stay at the station more enjoyable. To discover which aspects the customer perceives as important, NS developed a research method that is based on enviromnental psychology and with which the impact of passengers＇ waiting and station experience can be measured. This article addresses the measures taken, the method of measurement and the measurement results. Examples of such measures are： experimenting with colour, light, music, infotainment and increasing and repositioning the shopping facilities. Our studies not only showed an increase in the score for the general evaluation of a test station （Leiden Central Station） with one full point but also significant positive effects on various aspects of waiting and experience.展开更多
The similarities and differences of ASTM and China GB standard are studied in three aspects:measure instrument,terminology and applicable field.They are similar on the measuring apparatus and GB has less measurements,...The similarities and differences of ASTM and China GB standard are studied in three aspects:measure instrument,terminology and applicable field.They are similar on the measuring apparatus and GB has less measurements,such as girth,length and width measurements than ASTM and it lack across chest width,back width,total crotch length and shoulder slope which are important measurements in pattern making.ASTM classifies its standards according to the customers' size,gender and age.So we think GB standard could make some modifications from these fields to satisfy the users.展开更多
The accurate characterization of thermoelectric properties at low temperatures is crucial for the development of high-performance thermoelectric cooling devices. While measurement errors of thermoelectric properties a...The accurate characterization of thermoelectric properties at low temperatures is crucial for the development of high-performance thermoelectric cooling devices. While measurement errors of thermoelectric properties at temperatures above room temperature have been extensively discussed, there is a lack of standard measurement protocols and error analyses for low-temperature transport properties. In this study, we present a measurement system capable of characterizing all three key thermoelectric parameters, i.e., Seebeck coefficient, electrical conductivity, and thermal conductivity, for a single sample across a temperature range of 10 K to 300 K. We investigated six representative commercial Bi_(2)Te_(3)-based samples(three N-type and three P-type). Using an error propagation model, we systematically analyzed the measurement uncertainties of the three intrinsic parameters and the resulting thermoelectric figure of merit. Our findings reveal that measurement uncertainties for both N-type and P-type Bi_(2)Te_(3)-based materials can be effectively maintained below 5% in the temperature range of 40 K to 300 K. However, the uncertainties increase to over 10% at lower temperatures, primarily due to the relatively smaller values of electrical resistivity and Seebeck coefficients in this regime. This work establishes foundational data for Bi_(2)Te_(3)-based thermoelectric materials and provides a framework for broader investigations of advanced low-temperature thermoelectrics.展开更多
During the 13^(th) Five-Year Plan,China's natural gas industry developed rapidly,and a diversified supply and marketing pattern was formed,including domestic conventional gas,unconventional gas(shale gas,tight san...During the 13^(th) Five-Year Plan,China's natural gas industry developed rapidly,and a diversified supply and marketing pattern was formed,including domestic conventional gas,unconventional gas(shale gas,tight sandstone gas,coalbed methane,etc.),coal-based synthetic natural gas,imported LNG and imported pipeline gas.The gross calorific value of gas sources ranged from 34 MJ/m^(3) to 43 MJ/m^(3),and the maximum difference of calorific value between different gas sources exceeded 20%.On May 24th,2019,the National Development and Reform Commission and other three ministries/commissions jointly issued the Supervision Regulation on the Fair Access of Oil and Gas Pipeline Network Facilities and required that a natural gas energy measuring and pricing system shall be established within 24 months from the implementation date of this Regulation.In order to speed up the construction of China's natural gas energy measuring system,this paper summarizes domestic achievements in the construction of natural gas energy measuring system from the aspects of value traceability and energy measurement standard,and analyzes natural gas flowrate measurement technology,calorific value determination technology,value traceability,localization,intelligentization and application technology of key energy measurement equipment,natural gas pipeline network energy balancing technology based on big data analysis,multi-source quality tracking and monitoring technology,and energy measurement standard system,the need of new energy detection and measurement technology,and put forward strategy for the development of natural gas measuring in China.And the following research results are obtained.First,China's natural gas energy measuring system can basically meet the requirements of implementing natural gas energy measurement,but it still falls behind the international leading level in terms of calibration and application of high-level flowmeter(such as 0.5 class),high-accuracy gas reference material,level of calorific value reference equipment,and measurement standard system,and needs to be further improved.Second,it is necessary for China to speed up the research and application of the localization and intelligentization technologies of key energy measurement equipment.Third,natural gas pipeline network shall be equipped with measurement check method,energy balancing system based on big data analysis,and multi-source quality tracking and monitoring system,so that the energy transmission loss index of natural gas pipeline network can be superior to the international leading level(0.10%).Fourth,to realize the largescale application of hydrogen energy and bio-energy and the mixed transportation of hydrogen,bio-methane and natural gas,it is necessary to carry out research on new technology and standardization of hydrogen/bio-methane blended natural gas detection and measurement.展开更多
We introduce notions of ordinary and standard products of a-finite measures and prove their existence. This approach allows us to construct invariant extensions of ordinary and standard products of Haar measures. In p...We introduce notions of ordinary and standard products of a-finite measures and prove their existence. This approach allows us to construct invariant extensions of ordinary and standard products of Haar measures. In particular, we construct translation-invariant extensions of ordinary and standard Lebesgue measures on R∞ and Rogers-Fremlin measures on l∞, respectively, such that topological weights of quasi-metric spaces associated with these measures are maximal （i.e., 2c）. We also solve some Fremlin problems concerned with an existence of uniform measures in Banach spaces.展开更多
Current studies on blasting construction of small clear-distance tunnels have not considered the impact of existing tunnel lining defects when establishing safety controls.This paper offers a series of study results b...Current studies on blasting construction of small clear-distance tunnels have not considered the impact of existing tunnel lining defects when establishing safety controls.This paper offers a series of study results based on the blasting project of a new tunnel adjacent to the existing defect Xinling tunnel to thoroughly examine the dynamic response,safety control standards,and measures of the existing defect tunnel.First,structural models were developed to investigate the influence of the presence or absence of specific defects(like lining cracks and cavities behind the lining)on the dynamic response of the current tunnel lining to identify the most unfavorable defect distribution.Then,establish safety control standards for intact linings and those with the most unfavorable defects.Eventually,two types of control measures,single safe charge and reasonable delay time,were studied based on the established safety control standards.In particular,the most adverse position of cracks was the wall facing the explosion,the rise in depth was more unfavorable for vibration response,and the impact of the longitudinal crack was restricted to the vicinity of the crack.While the vault was the most adverse cavity position,the rise in cavity area was more damaging,and the influence range varied with longitudinal cavity length.Moreover,the impact of cracks was mainly evident in the amplification effect of stress at the crack region.In contrast,cavities had varied degrees of amplification effects on the vibration velocity and stress response and a relatively extensive influence range.Safety control research was conducted,when the tunnel was intact,with a right wall crack,a vault cavity,and both vault cavity and crack for this project,the peak particle velocity(PPV)of the safety control standard for vibration velocity was 13,10,13,and 8 cm/s,respectively,and the respective single safe charge could be adjusted at 64,53,37,and 25 kg.However,the presence of different defects had a relatively negligible effect on the reasonable delay time;25 ms was recommended for existing tunnel lining with and without the defect.展开更多
文摘Stations are often regarded as change engines--places where passengers have to change as quickly and efficiently as possible from one mode of transport to another. Underpinned by research, NS （Netherlands Railways） currently takes the view that stations should be transformed into dynamic urban portals that not only facilitate a speedy transfer but also make the stay at the station more enjoyable. To discover which aspects the customer perceives as important, NS developed a research method that is based on enviromnental psychology and with which the impact of passengers＇ waiting and station experience can be measured. This article addresses the measures taken, the method of measurement and the measurement results. Examples of such measures are： experimenting with colour, light, music, infotainment and increasing and repositioning the shopping facilities. Our studies not only showed an increase in the score for the general evaluation of a test station （Leiden Central Station） with one full point but also significant positive effects on various aspects of waiting and experience.
文摘The similarities and differences of ASTM and China GB standard are studied in three aspects:measure instrument,terminology and applicable field.They are similar on the measuring apparatus and GB has less measurements,such as girth,length and width measurements than ASTM and it lack across chest width,back width,total crotch length and shoulder slope which are important measurements in pattern making.ASTM classifies its standards according to the customers' size,gender and age.So we think GB standard could make some modifications from these fields to satisfy the users.
基金supported by the National Natural Science Foundation of China (Grant No. 52172259)the National Key Research and Development Program of China (Grant Nos. 2021YFA0718700 and 2022YFB3803900)the Fundamental Research Funds for the Inner Mongolia Normal University (Grant No. 2022JBTD008)。
文摘The accurate characterization of thermoelectric properties at low temperatures is crucial for the development of high-performance thermoelectric cooling devices. While measurement errors of thermoelectric properties at temperatures above room temperature have been extensively discussed, there is a lack of standard measurement protocols and error analyses for low-temperature transport properties. In this study, we present a measurement system capable of characterizing all three key thermoelectric parameters, i.e., Seebeck coefficient, electrical conductivity, and thermal conductivity, for a single sample across a temperature range of 10 K to 300 K. We investigated six representative commercial Bi_(2)Te_(3)-based samples(three N-type and three P-type). Using an error propagation model, we systematically analyzed the measurement uncertainties of the three intrinsic parameters and the resulting thermoelectric figure of merit. Our findings reveal that measurement uncertainties for both N-type and P-type Bi_(2)Te_(3)-based materials can be effectively maintained below 5% in the temperature range of 40 K to 300 K. However, the uncertainties increase to over 10% at lower temperatures, primarily due to the relatively smaller values of electrical resistivity and Seebeck coefficients in this regime. This work establishes foundational data for Bi_(2)Te_(3)-based thermoelectric materials and provides a framework for broader investigations of advanced low-temperature thermoelectrics.
基金Project supported by the CNPC’s Scientific Research Project“Study on Application of Natural Gas Energy Measurement”(No.:2018D-5001-0511).
文摘During the 13^(th) Five-Year Plan,China's natural gas industry developed rapidly,and a diversified supply and marketing pattern was formed,including domestic conventional gas,unconventional gas(shale gas,tight sandstone gas,coalbed methane,etc.),coal-based synthetic natural gas,imported LNG and imported pipeline gas.The gross calorific value of gas sources ranged from 34 MJ/m^(3) to 43 MJ/m^(3),and the maximum difference of calorific value between different gas sources exceeded 20%.On May 24th,2019,the National Development and Reform Commission and other three ministries/commissions jointly issued the Supervision Regulation on the Fair Access of Oil and Gas Pipeline Network Facilities and required that a natural gas energy measuring and pricing system shall be established within 24 months from the implementation date of this Regulation.In order to speed up the construction of China's natural gas energy measuring system,this paper summarizes domestic achievements in the construction of natural gas energy measuring system from the aspects of value traceability and energy measurement standard,and analyzes natural gas flowrate measurement technology,calorific value determination technology,value traceability,localization,intelligentization and application technology of key energy measurement equipment,natural gas pipeline network energy balancing technology based on big data analysis,multi-source quality tracking and monitoring technology,and energy measurement standard system,the need of new energy detection and measurement technology,and put forward strategy for the development of natural gas measuring in China.And the following research results are obtained.First,China's natural gas energy measuring system can basically meet the requirements of implementing natural gas energy measurement,but it still falls behind the international leading level in terms of calibration and application of high-level flowmeter(such as 0.5 class),high-accuracy gas reference material,level of calorific value reference equipment,and measurement standard system,and needs to be further improved.Second,it is necessary for China to speed up the research and application of the localization and intelligentization technologies of key energy measurement equipment.Third,natural gas pipeline network shall be equipped with measurement check method,energy balancing system based on big data analysis,and multi-source quality tracking and monitoring system,so that the energy transmission loss index of natural gas pipeline network can be superior to the international leading level(0.10%).Fourth,to realize the largescale application of hydrogen energy and bio-energy and the mixed transportation of hydrogen,bio-methane and natural gas,it is necessary to carry out research on new technology and standardization of hydrogen/bio-methane blended natural gas detection and measurement.
基金Supported by National Science Foundation of Georgia （Grants Nos. GNSF/ST 08/3-391, Sh. Rustaveli GNSF/ST 09_144-3-105）
文摘We introduce notions of ordinary and standard products of a-finite measures and prove their existence. This approach allows us to construct invariant extensions of ordinary and standard products of Haar measures. In particular, we construct translation-invariant extensions of ordinary and standard Lebesgue measures on R∞ and Rogers-Fremlin measures on l∞, respectively, such that topological weights of quasi-metric spaces associated with these measures are maximal （i.e., 2c）. We also solve some Fremlin problems concerned with an existence of uniform measures in Banach spaces.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2034205,and 52178397)。
文摘Current studies on blasting construction of small clear-distance tunnels have not considered the impact of existing tunnel lining defects when establishing safety controls.This paper offers a series of study results based on the blasting project of a new tunnel adjacent to the existing defect Xinling tunnel to thoroughly examine the dynamic response,safety control standards,and measures of the existing defect tunnel.First,structural models were developed to investigate the influence of the presence or absence of specific defects(like lining cracks and cavities behind the lining)on the dynamic response of the current tunnel lining to identify the most unfavorable defect distribution.Then,establish safety control standards for intact linings and those with the most unfavorable defects.Eventually,two types of control measures,single safe charge and reasonable delay time,were studied based on the established safety control standards.In particular,the most adverse position of cracks was the wall facing the explosion,the rise in depth was more unfavorable for vibration response,and the impact of the longitudinal crack was restricted to the vicinity of the crack.While the vault was the most adverse cavity position,the rise in cavity area was more damaging,and the influence range varied with longitudinal cavity length.Moreover,the impact of cracks was mainly evident in the amplification effect of stress at the crack region.In contrast,cavities had varied degrees of amplification effects on the vibration velocity and stress response and a relatively extensive influence range.Safety control research was conducted,when the tunnel was intact,with a right wall crack,a vault cavity,and both vault cavity and crack for this project,the peak particle velocity(PPV)of the safety control standard for vibration velocity was 13,10,13,and 8 cm/s,respectively,and the respective single safe charge could be adjusted at 64,53,37,and 25 kg.However,the presence of different defects had a relatively negligible effect on the reasonable delay time;25 ms was recommended for existing tunnel lining with and without the defect.
