On August 20, 2002, the construction-starting ceremonies of the north-channel projects for sending power from west to east were solemnly held at one main meeting place and five sub-meeting places simultaneously. The n...On August 20, 2002, the construction-starting ceremonies of the north-channel projects for sending power from west to east were solemnly held at one main meeting place and five sub-meeting places simultaneously. The north-channel projects for sending power from west to east started to construct this time include three transmission and substation projects and four power source projects. This paper makes a brief introduction to the seven projects.展开更多
Migration is one of the most prominent phenomena in these ultimate years.It has brought some good consequences and economic development,but also a number of socio-economical and socio-political problems,such as decrea...Migration is one of the most prominent phenomena in these ultimate years.It has brought some good consequences and economic development,but also a number of socio-economical and socio-political problems,such as decreasing population in the sending countries,brain drain,labour market shortages,etc.This paper focuses on the reasons why people emigrate from their countries of origin and what effects bring their emigration to the national economy.The purpose of the paper is to explain the emigration impact on the labour market in the sending countries,the phenomenon“brain drain”and its effects,the impact of the remittances,and the importance of Diasporas and return migration for the countries of origin.展开更多
In this paper, a modified access mechanism named Constrained-send DCF (CDCF) is proposed to improve the performance of IEEE 802.11 DCF protocol. It is found that, in DCF, the transmission probability is higher than th...In this paper, a modified access mechanism named Constrained-send DCF (CDCF) is proposed to improve the performance of IEEE 802.11 DCF protocol. It is found that, in DCF, the transmission probability is higher than the reasonable value when the node number is greater than 4 under basic access scheme or than 17 under RTS/CTS scheme, and it results in serious collision. To avoid collision of high access loading, a constrained-send probability is introduced at the end of each back off procedure for the station transmitting. The performance of this mechanism is analyzed based on a 2-Dimension Markov analytical model, after that the optimum constrained-send probability is derived. Numerical results show that the CDCF mechanism has much better performance than DCF with respect to both system throughput and average packet delay. And under RTS/CTS scheme, although CDCF slightly improve the throughput performance (due to the natural good throughput performance of RTS/CTS-scheme DCF), it leads to a much better average packet delay performance compared to DCF. The CDCF keeps all the features of the IEEE 802.11 DCF protocol and is quite easy to implement.展开更多
The Data Timed Sending (DTS) protocol contributes to the energy savings in Wireless Sensor Networks (WSNs) and prolongs the sensor nodes’ battery lifetime. DTS saves energy by transmitting short packets, without data...The Data Timed Sending (DTS) protocol contributes to the energy savings in Wireless Sensor Networks (WSNs) and prolongs the sensor nodes’ battery lifetime. DTS saves energy by transmitting short packets, without data payload, from the sensor nodes to the base station or the cluster head according to the Time Division Multiple Access (TDMA) scheduling. Placing the short packets into appropriate slots and subslots in the TDMA frames transfers the information about the measured values and node identity. This paper presents the proof of concept of the proposed DTS protocol and provides verification of the energy savings using the QualNet®communication simulation platform (QualNet) and the SunTM Small Programmable Object Technology (Sun SPOT) testbed platform (for single hop and multi hop scenarios). The simulations and the testbed measurements confirm that the DTS protocol can provide energy savings up to 30% when compared with the IEEE 802.15.4 standard in unslotted Carrier Sense Multiple Access with Collision Avoidance (CSMA-CA) mode at 2.4 GHz frequency band.展开更多
The contracts worth $ 720 million for importing 1st phase project equipment of Yangcheng Coal-fired Power Plant were signed on August 22, 1996 in Beijing between the China Electric Power Technology Import & Export...The contracts worth $ 720 million for importing 1st phase project equipment of Yangcheng Coal-fired Power Plant were signed on August 22, 1996 in Beijing between the China Electric Power Technology Import & Export Corp., Shanxi’s Yangcheng International Power Generating Co. Ltd, Shanxi Provincial Power Corp., Germany’s Siemens and the US firm Foster Wheeler Energy Corp.展开更多
Designing an Ethernet switch that can assure normal interaction of protocol packets between switches in a network environment of massive traffic is an important matter. Taking the L3 Ethernet switch based on Applicati...Designing an Ethernet switch that can assure normal interaction of protocol packets between switches in a network environment of massive traffic is an important matter. Taking the L3 Ethernet switch based on Application Specific Integrated Circuit (ASIC) as an example,this article analyzes several typical issues about packet receiving and sending by the CPU in a multi-progress environment,including CPU load,software and hardware queue settings,and communication mechanism between CPU and the switch chip. This article gives solutions to these issues mentioned above. The solutions are applicable to Network Processor (NP) issues as well.展开更多
On August 1st, the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) convened a conference to transmit the spirit of national quality work and study an important speech regarding sta... On August 1st, the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) convened a conference to transmit the spirit of national quality work and study an important speech regarding standards from Wen Jiabao,Premier of the State Council.……展开更多
Two satellites were sent into space aboard a LM-4B launch vehicle from the Taiyuan Satellite Launch Center at 06:25 Beijing time on April 30.The Tianhui 2 satellite was placed to a SSO orbit.This was the 303rd launch ...Two satellites were sent into space aboard a LM-4B launch vehicle from the Taiyuan Satellite Launch Center at 06:25 Beijing time on April 30.The Tianhui 2 satellite was placed to a SSO orbit.This was the 303rd launch of the LM series launch vehicle and the first mission of the Shanghai Academy of Spaceflight Technology in 2019.展开更多
Chinese optical fiber maker is becoming a major player in global markets By Yu Nanfiber was invented in 1970, a breakthrough innovation that changed the world. Six years later, the first optical fiber in China was ins...Chinese optical fiber maker is becoming a major player in global markets By Yu Nanfiber was invented in 1970, a breakthrough innovation that changed the world. Six years later, the first optical fiber in China was installed by the FiberHome Technol- ogies Group. then a fledgling information and telecom- munication product and solution provider. Since then, the optical fiber maker based in Wuhan. central China＇s Hubei Province, has grown into an ＂optical communications expert.＂展开更多
THERE＇S good news for football fans in Africa who have been sighing over the end of 2016 UEFA Eu- ropean Championship, Now they can switch to watch- ing Chinese Super League （CSL）, China＇s highest tier of professi...THERE＇S good news for football fans in Africa who have been sighing over the end of 2016 UEFA Eu- ropean Championship, Now they can switch to watch- ing Chinese Super League （CSL）, China＇s highest tier of professional football, which kicked off its 13th edition in March with the finale scheduled on November 5.展开更多
A new business was opening and one of the owners friends wanted to send him flowers for theoccasion.The flowers arrived at the new business sight and the owner read the card:“Rest in Peace.”The owner was very angry,...A new business was opening and one of the owners friends wanted to send him flowers for theoccasion.The flowers arrived at the new business sight and the owner read the card:“Rest in Peace.”The owner was very angry,to say the least,and called to complain.“Sir, I m really sorry for themistake,and sorry you were offended,”said the florist.“But even worse,somewhere there is afuneral taking place today,and they have flowers with a note saying,‘Congratulations on your newlocation.’”展开更多
文摘On August 20, 2002, the construction-starting ceremonies of the north-channel projects for sending power from west to east were solemnly held at one main meeting place and five sub-meeting places simultaneously. The north-channel projects for sending power from west to east started to construct this time include three transmission and substation projects and four power source projects. This paper makes a brief introduction to the seven projects.
文摘Migration is one of the most prominent phenomena in these ultimate years.It has brought some good consequences and economic development,but also a number of socio-economical and socio-political problems,such as decreasing population in the sending countries,brain drain,labour market shortages,etc.This paper focuses on the reasons why people emigrate from their countries of origin and what effects bring their emigration to the national economy.The purpose of the paper is to explain the emigration impact on the labour market in the sending countries,the phenomenon“brain drain”and its effects,the impact of the remittances,and the importance of Diasporas and return migration for the countries of origin.
基金Sponsored by the National Natural Science Foundation of China(Grant No.60832008)the National S&T Major Project (Grant No.2010ZX03003-002-02)the National Key Basic Research and Development Project (Grant No.2012CB316006)
文摘In this paper, a modified access mechanism named Constrained-send DCF (CDCF) is proposed to improve the performance of IEEE 802.11 DCF protocol. It is found that, in DCF, the transmission probability is higher than the reasonable value when the node number is greater than 4 under basic access scheme or than 17 under RTS/CTS scheme, and it results in serious collision. To avoid collision of high access loading, a constrained-send probability is introduced at the end of each back off procedure for the station transmitting. The performance of this mechanism is analyzed based on a 2-Dimension Markov analytical model, after that the optimum constrained-send probability is derived. Numerical results show that the CDCF mechanism has much better performance than DCF with respect to both system throughput and average packet delay. And under RTS/CTS scheme, although CDCF slightly improve the throughput performance (due to the natural good throughput performance of RTS/CTS-scheme DCF), it leads to a much better average packet delay performance compared to DCF. The CDCF keeps all the features of the IEEE 802.11 DCF protocol and is quite easy to implement.
文摘The Data Timed Sending (DTS) protocol contributes to the energy savings in Wireless Sensor Networks (WSNs) and prolongs the sensor nodes’ battery lifetime. DTS saves energy by transmitting short packets, without data payload, from the sensor nodes to the base station or the cluster head according to the Time Division Multiple Access (TDMA) scheduling. Placing the short packets into appropriate slots and subslots in the TDMA frames transfers the information about the measured values and node identity. This paper presents the proof of concept of the proposed DTS protocol and provides verification of the energy savings using the QualNet®communication simulation platform (QualNet) and the SunTM Small Programmable Object Technology (Sun SPOT) testbed platform (for single hop and multi hop scenarios). The simulations and the testbed measurements confirm that the DTS protocol can provide energy savings up to 30% when compared with the IEEE 802.15.4 standard in unslotted Carrier Sense Multiple Access with Collision Avoidance (CSMA-CA) mode at 2.4 GHz frequency band.
文摘The contracts worth $ 720 million for importing 1st phase project equipment of Yangcheng Coal-fired Power Plant were signed on August 22, 1996 in Beijing between the China Electric Power Technology Import & Export Corp., Shanxi’s Yangcheng International Power Generating Co. Ltd, Shanxi Provincial Power Corp., Germany’s Siemens and the US firm Foster Wheeler Energy Corp.
文摘Designing an Ethernet switch that can assure normal interaction of protocol packets between switches in a network environment of massive traffic is an important matter. Taking the L3 Ethernet switch based on Application Specific Integrated Circuit (ASIC) as an example,this article analyzes several typical issues about packet receiving and sending by the CPU in a multi-progress environment,including CPU load,software and hardware queue settings,and communication mechanism between CPU and the switch chip. This article gives solutions to these issues mentioned above. The solutions are applicable to Network Processor (NP) issues as well.
文摘 On August 1st, the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) convened a conference to transmit the spirit of national quality work and study an important speech regarding standards from Wen Jiabao,Premier of the State Council.……
文摘Two satellites were sent into space aboard a LM-4B launch vehicle from the Taiyuan Satellite Launch Center at 06:25 Beijing time on April 30.The Tianhui 2 satellite was placed to a SSO orbit.This was the 303rd launch of the LM series launch vehicle and the first mission of the Shanghai Academy of Spaceflight Technology in 2019.
文摘Chinese optical fiber maker is becoming a major player in global markets By Yu Nanfiber was invented in 1970, a breakthrough innovation that changed the world. Six years later, the first optical fiber in China was installed by the FiberHome Technol- ogies Group. then a fledgling information and telecom- munication product and solution provider. Since then, the optical fiber maker based in Wuhan. central China＇s Hubei Province, has grown into an ＂optical communications expert.＂
文摘THERE＇S good news for football fans in Africa who have been sighing over the end of 2016 UEFA Eu- ropean Championship, Now they can switch to watch- ing Chinese Super League （CSL）, China＇s highest tier of professional football, which kicked off its 13th edition in March with the finale scheduled on November 5.
文摘A new business was opening and one of the owners friends wanted to send him flowers for theoccasion.The flowers arrived at the new business sight and the owner read the card:“Rest in Peace.”The owner was very angry,to say the least,and called to complain.“Sir, I m really sorry for themistake,and sorry you were offended,”said the florist.“But even worse,somewhere there is afuneral taking place today,and they have flowers with a note saying,‘Congratulations on your newlocation.’”
