Mega shopping mall projects have seen dramatic growth and great development in recent years in Egypt. Many new mega shopping mall projects are under construction and expecting to start working in the few coming years....Mega shopping mall projects have seen dramatic growth and great development in recent years in Egypt. Many new mega shopping mall projects are under construction and expecting to start working in the few coming years. In the absence of researches studying the Egyptian mega shopping mall projects, this study tries to highlight the most critical risks that face these projects and the associated most effective response methods to be employed. The scope covers the analysis from different perspectives by including owners/developers, designers, consultants, project managers, and contractors that have previous experience in large-scale projects such as shopping mall projects. In this study, 30 construction project risks are classified into six main categories according to their type and 150 risk mitigation/elimination measures are introduced to overcome the impact of risks under each of these risk categories. The results reveal that the main risk category that faces the mega shopping mall projects in Egypt is the one including the financial risk factors. The most critical risk factor that faces these projects is the financial ability of the client. These results are similar to findings by previous researches conducted for large projects in other countries.展开更多
The accurate measurement method of ultrasonic velocity by the pulse interference method with eliminating the diffraction effect has been investigated in VHF range experimentally. Two silicate glasses were taken as the...The accurate measurement method of ultrasonic velocity by the pulse interference method with eliminating the diffraction effect has been investigated in VHF range experimentally. Two silicate glasses were taken as the specimens, their frequency dependences of longitudinal velocities were measured in the frequency range 50-350 MHz, and the phase advances of ultrasonic signals caused by diffraction effect were calculated using A. O. Williams' theoretical expression. For the frequency dependences of longitudinal velocities, the measurement results were in good agreement with the simulation ones in which the phase advances were included. It has been shown that the velocity error due to diffraction effect can be corrected very well by this method.展开更多
The construction industry is indispensable in the national economic construction, so it is very important to ensure the healthy development of the construction industry. Building structure design is the beginning of c...The construction industry is indispensable in the national economic construction, so it is very important to ensure the healthy development of the construction industry. Building structure design is the beginning of construction engineering, which has a direct impact on whether the project can be carried out smoothly and the quality of the project. Therefore, as relevant designers, we must correctly view the current safety risks existing in the building structure design, and then improve the safety risks of various building structure design, so as to improve the design quality, promote the smooth development of construction projects, and finally provide power for the healthy development of China's construction industry. Based on this, this paper briefly expounds the hidden dangers of building structure design.展开更多
This paper proposes a differential mode measurement and control system(DMCS)for differential MEMS resonant accelerometer(DMRA),which operates the differential resonators of the DMRA at different vibration modes.Unlike...This paper proposes a differential mode measurement and control system(DMCS)for differential MEMS resonant accelerometer(DMRA),which operates the differential resonators of the DMRA at different vibration modes.Unlike traditional DMRA,the first resonator of the differential resonator operates in the first-order mode(R1M1),and the second resonator operates in the second-order mode(R2M2).Within the measurement range of DMRA,the frequencies of the two resonators will not cross,so there will be no mutual interference.This ensures the structural symmetry of the DMRA while avoiding the measurement dead zone phenomenon caused by the coupling of the differential vibration beam at similar resonant frequencies.The structural symmetry of the differential resonator ensures good temperature consistency of the differential vibration beam,and the consistency of the temperature frequency coefficient matches well,which enables the differential resonator to strongly suppress the temperatureinduced common-mode effects.During the temperature cycling process between-20℃ and 80℃,the equivalent acceleration drift of R1M1 and R2M2 were 341.6 mg and 414.6 mg,respectively.After using the differential temperature compensation algorithm,the equivalent acceleration drift was reduced to 1.19 mg.The minimum Allan variance measured statically at room temperature decreased from 1.42μg@0.85 s for R1M1 and 1.52μg@0.85 s for R2M2 to 0.23μg@7.15 s,indicating a significant improvement in the long-term stability of DMRA.In addition,the differential measuring method also eliminated common mode ambient noise in low frequency range,ultimately achieving a noise level of 220 ng=ffiffiffiffiffi Hz p@(0.2–0.8 Hz)for a prototype device with a measurement range exceeding±5 g.展开更多
文摘Mega shopping mall projects have seen dramatic growth and great development in recent years in Egypt. Many new mega shopping mall projects are under construction and expecting to start working in the few coming years. In the absence of researches studying the Egyptian mega shopping mall projects, this study tries to highlight the most critical risks that face these projects and the associated most effective response methods to be employed. The scope covers the analysis from different perspectives by including owners/developers, designers, consultants, project managers, and contractors that have previous experience in large-scale projects such as shopping mall projects. In this study, 30 construction project risks are classified into six main categories according to their type and 150 risk mitigation/elimination measures are introduced to overcome the impact of risks under each of these risk categories. The results reveal that the main risk category that faces the mega shopping mall projects in Egypt is the one including the financial risk factors. The most critical risk factor that faces these projects is the financial ability of the client. These results are similar to findings by previous researches conducted for large projects in other countries.
文摘The accurate measurement method of ultrasonic velocity by the pulse interference method with eliminating the diffraction effect has been investigated in VHF range experimentally. Two silicate glasses were taken as the specimens, their frequency dependences of longitudinal velocities were measured in the frequency range 50-350 MHz, and the phase advances of ultrasonic signals caused by diffraction effect were calculated using A. O. Williams' theoretical expression. For the frequency dependences of longitudinal velocities, the measurement results were in good agreement with the simulation ones in which the phase advances were included. It has been shown that the velocity error due to diffraction effect can be corrected very well by this method.
文摘The construction industry is indispensable in the national economic construction, so it is very important to ensure the healthy development of the construction industry. Building structure design is the beginning of construction engineering, which has a direct impact on whether the project can be carried out smoothly and the quality of the project. Therefore, as relevant designers, we must correctly view the current safety risks existing in the building structure design, and then improve the safety risks of various building structure design, so as to improve the design quality, promote the smooth development of construction projects, and finally provide power for the healthy development of China's construction industry. Based on this, this paper briefly expounds the hidden dangers of building structure design.
基金supported in part by the National Key Research and Development Program of China under Grant 2022YFB3207301Shandong Provincial Natural Science Foundation under Grant No.ZR2024ZD08.
文摘This paper proposes a differential mode measurement and control system(DMCS)for differential MEMS resonant accelerometer(DMRA),which operates the differential resonators of the DMRA at different vibration modes.Unlike traditional DMRA,the first resonator of the differential resonator operates in the first-order mode(R1M1),and the second resonator operates in the second-order mode(R2M2).Within the measurement range of DMRA,the frequencies of the two resonators will not cross,so there will be no mutual interference.This ensures the structural symmetry of the DMRA while avoiding the measurement dead zone phenomenon caused by the coupling of the differential vibration beam at similar resonant frequencies.The structural symmetry of the differential resonator ensures good temperature consistency of the differential vibration beam,and the consistency of the temperature frequency coefficient matches well,which enables the differential resonator to strongly suppress the temperatureinduced common-mode effects.During the temperature cycling process between-20℃ and 80℃,the equivalent acceleration drift of R1M1 and R2M2 were 341.6 mg and 414.6 mg,respectively.After using the differential temperature compensation algorithm,the equivalent acceleration drift was reduced to 1.19 mg.The minimum Allan variance measured statically at room temperature decreased from 1.42μg@0.85 s for R1M1 and 1.52μg@0.85 s for R2M2 to 0.23μg@7.15 s,indicating a significant improvement in the long-term stability of DMRA.In addition,the differential measuring method also eliminated common mode ambient noise in low frequency range,ultimately achieving a noise level of 220 ng=ffiffiffiffiffi Hz p@(0.2–0.8 Hz)for a prototype device with a measurement range exceeding±5 g.
