SalenMX has drawn much attention recently,because it is nonsensitive to moisture and effective for copolymerization of CO2 and epoxides.However,usually expensive organic metal compounds were used.A low cost procedure ...SalenMX has drawn much attention recently,because it is nonsensitive to moisture and effective for copolymerization of CO2 and epoxides.However,usually expensive organic metal compounds were used.A low cost procedure of SalenMX preparation is described that SalenAl（OPr） can be obtained by using aluminium iso-propoxide reacted with SalenH2 in tetrahydrofuran at room temperature overnight.The catalyst precursor Schiff-base SalenH2 （N,N′-Bis（salicylidene）-1,2-phenylenediamine） was synthesized by refluxing 2 equiv salicylaldehyde and 1 equiv of 1,2-phenylendiamine in methnol for a period of time.SalenH2 and SalenAl（OPr） were characterized by FT-IR,mass Spectroscopy,UV-Vis and 1H-NMR.The copolymerization of carbon dioxide and cyclohexene oxide（CHO） was carried out at 80℃ for a certain period time using 50 mg SalenAl（OPr） as catalyst.SalenAl（OPr） had been shown to be an effective catalyst for the copolymerization of CO2 and CHO along with a small quantity of byproduct cyclic carbonate.The addition of various cocatalysts,including DMAP,N-MeIm,DBU and Bu4NCl or Bu4NBr salts can greatly enhance the rate of copolymerization.The copolymers were produced with >95% carbonate linkages and <5% cyclic carbonates.The highest catalytic efficiency is 190 g copolymer per g catalyst.展开更多
Purpose: To understand how authors and reviewers are accepting and embracing Open Peer Review(OPR), one of the newest innovations in the Open Science movement.Design/methodology/approach: This research collected and a...Purpose: To understand how authors and reviewers are accepting and embracing Open Peer Review(OPR), one of the newest innovations in the Open Science movement.Design/methodology/approach: This research collected and analyzed data from the Open Access journal Peer J over its first three years(2013–2016). Web data were scraped, cleaned, and structured using several Web tools and programs. The structured data were imported into a relational database. Data analyses were conducted using analytical tools as well as programs developed by the researchers.Findings: Peer J, which supports optional OPR, has a broad international representation of authors and referees. Approximately 73.89% of articles provide full review histories. Of the articles with published review histories, 17.61% had identities of all reviewers and 52.57% had at least one signed reviewer. In total, 43.23% of all reviews were signed. The observed proportions of signed reviews have been relatively stable over the period since the Journal’s inception.Research limitations: This research is constrained by the availability of the peer review history data. Some peer reviews were not available when the authors opted out of publishing their review histories. The anonymity of reviewers made it impossible to give an accurate count of reviewers who contributed to the review process. Practical implications: These findings shed light on the current characteristics of OPR. Given the policy that authors are encouraged to make their articles’ review history public and referees are encouraged to sign their review reports, the three years of Peer J review data demonstrate that there is still some reluctance by authors to make their reviews public and by reviewers to identify themselves. Originality/value: This is the first study to closely examine Peer J as an example of an OPR model journal. As Open Science moves further towards open research, OPR is a final and critical component. Research in this area must identify the best policies and paths towards a transparent and open peer review process for scientific communication.展开更多
Control rod is used to change the power in nuclear reactor.?Certainly, the core at any moment can be made subcritical condition and shut downs when occurring?to emergency instance in the core. The rod is grouped based...Control rod is used to change the power in nuclear reactor.?Certainly, the core at any moment can be made subcritical condition and shut downs when occurring?to emergency instance in the core. The rod is grouped based?on their function and located at different places in the core where their feature is maximized.?Two methods of control rod calibration are the asymptotic period method and the rod-drop method, which were applied in this experiment. In the first method, the reactor is made supcritical by inserting the control rod to be calibrated a certain level. The rod drop method is to determine the subcritical;at the critical state, the rod to be calibrated is dropped into the core, and the resulting decay of neutron flux is observed and related to the reactivity. In this paper, the regulating rod will be calibrated according to the reactivity in OPR-1000 that corresponds to a certain control rod insert or withdraw, and the reactivity in power reactor depends?on the integral and differential control rod group too. The core simulator OPR1000 is used to test those methods.展开更多
Blade vibration monitoring can ensure the safe operation of aeroengine rotor blades.Among the methods of blade vibration monitoring,Blade Tip Timing(BTT)method has attracted more and more attention because of its adva...Blade vibration monitoring can ensure the safe operation of aeroengine rotor blades.Among the methods of blade vibration monitoring,Blade Tip Timing(BTT)method has attracted more and more attention because of its advantages of non-contact measurement.However,it is difficult to install the Once-Per-Revolution(OPR)probe in the confined space of aeroengine,and the failure and instability of the OPR signal will reduce the reliability of the blade vibration analysis results,which directly affects the accuracy of the blade vibration parameters identification.The Multi-Probe linear fitting and Time of Arrival(ToA)Linear Correction method based on the BTT(MP-LC-BTT)without OPR is proposed to reduce the errors of single probe linear fitting method for blade vibration displacement analysis.The proposed method can also correct the calculation error of blade vibration displacement due to the nonlinear change of rotation speed,which can improve the analysis accuracy of the blade vibration displacement.A new blade vibration model conforming to the actual vibration characteristics is established,and the effectiveness of the proposed method is verified by numerical simulation.Finally,the reliability and accuracy of the MP-LC-BTT method have been verified by the experiments which include two high-speed blade test-benches and an industrial axial fan.This method can be used in the actual aero-engine monitoring instead of the BTT method with OPR.展开更多
文摘SalenMX has drawn much attention recently,because it is nonsensitive to moisture and effective for copolymerization of CO2 and epoxides.However,usually expensive organic metal compounds were used.A low cost procedure of SalenMX preparation is described that SalenAl（OPr） can be obtained by using aluminium iso-propoxide reacted with SalenH2 in tetrahydrofuran at room temperature overnight.The catalyst precursor Schiff-base SalenH2 （N,N′-Bis（salicylidene）-1,2-phenylenediamine） was synthesized by refluxing 2 equiv salicylaldehyde and 1 equiv of 1,2-phenylendiamine in methnol for a period of time.SalenH2 and SalenAl（OPr） were characterized by FT-IR,mass Spectroscopy,UV-Vis and 1H-NMR.The copolymerization of carbon dioxide and cyclohexene oxide（CHO） was carried out at 80℃ for a certain period time using 50 mg SalenAl（OPr） as catalyst.SalenAl（OPr） had been shown to be an effective catalyst for the copolymerization of CO2 and CHO along with a small quantity of byproduct cyclic carbonate.The addition of various cocatalysts,including DMAP,N-MeIm,DBU and Bu4NCl or Bu4NBr salts can greatly enhance the rate of copolymerization.The copolymers were produced with >95% carbonate linkages and <5% cyclic carbonates.The highest catalytic efficiency is 190 g copolymer per g catalyst.
文摘Purpose: To understand how authors and reviewers are accepting and embracing Open Peer Review(OPR), one of the newest innovations in the Open Science movement.Design/methodology/approach: This research collected and analyzed data from the Open Access journal Peer J over its first three years(2013–2016). Web data were scraped, cleaned, and structured using several Web tools and programs. The structured data were imported into a relational database. Data analyses were conducted using analytical tools as well as programs developed by the researchers.Findings: Peer J, which supports optional OPR, has a broad international representation of authors and referees. Approximately 73.89% of articles provide full review histories. Of the articles with published review histories, 17.61% had identities of all reviewers and 52.57% had at least one signed reviewer. In total, 43.23% of all reviews were signed. The observed proportions of signed reviews have been relatively stable over the period since the Journal’s inception.Research limitations: This research is constrained by the availability of the peer review history data. Some peer reviews were not available when the authors opted out of publishing their review histories. The anonymity of reviewers made it impossible to give an accurate count of reviewers who contributed to the review process. Practical implications: These findings shed light on the current characteristics of OPR. Given the policy that authors are encouraged to make their articles’ review history public and referees are encouraged to sign their review reports, the three years of Peer J review data demonstrate that there is still some reluctance by authors to make their reviews public and by reviewers to identify themselves. Originality/value: This is the first study to closely examine Peer J as an example of an OPR model journal. As Open Science moves further towards open research, OPR is a final and critical component. Research in this area must identify the best policies and paths towards a transparent and open peer review process for scientific communication.
文摘Control rod is used to change the power in nuclear reactor.?Certainly, the core at any moment can be made subcritical condition and shut downs when occurring?to emergency instance in the core. The rod is grouped based?on their function and located at different places in the core where their feature is maximized.?Two methods of control rod calibration are the asymptotic period method and the rod-drop method, which were applied in this experiment. In the first method, the reactor is made supcritical by inserting the control rod to be calibrated a certain level. The rod drop method is to determine the subcritical;at the critical state, the rod to be calibrated is dropped into the core, and the resulting decay of neutron flux is observed and related to the reactivity. In this paper, the regulating rod will be calibrated according to the reactivity in OPR-1000 that corresponds to a certain control rod insert or withdraw, and the reactivity in power reactor depends?on the integral and differential control rod group too. The core simulator OPR1000 is used to test those methods.
基金supports of the National Science and Technology Major Project,China(No.2017-Ⅲ-0009-0035)the Major Program of National Natural Science Foundation of China(No.51790513).
文摘Blade vibration monitoring can ensure the safe operation of aeroengine rotor blades.Among the methods of blade vibration monitoring,Blade Tip Timing(BTT)method has attracted more and more attention because of its advantages of non-contact measurement.However,it is difficult to install the Once-Per-Revolution(OPR)probe in the confined space of aeroengine,and the failure and instability of the OPR signal will reduce the reliability of the blade vibration analysis results,which directly affects the accuracy of the blade vibration parameters identification.The Multi-Probe linear fitting and Time of Arrival(ToA)Linear Correction method based on the BTT(MP-LC-BTT)without OPR is proposed to reduce the errors of single probe linear fitting method for blade vibration displacement analysis.The proposed method can also correct the calculation error of blade vibration displacement due to the nonlinear change of rotation speed,which can improve the analysis accuracy of the blade vibration displacement.A new blade vibration model conforming to the actual vibration characteristics is established,and the effectiveness of the proposed method is verified by numerical simulation.Finally,the reliability and accuracy of the MP-LC-BTT method have been verified by the experiments which include two high-speed blade test-benches and an industrial axial fan.This method can be used in the actual aero-engine monitoring instead of the BTT method with OPR.
