Laboratory-scale experiments were carried out to evaluate the influences of operational parameters on the melt crystallization efficiency for p-cresol purification.The optimal crystallization conditions were determine...Laboratory-scale experiments were carried out to evaluate the influences of operational parameters on the melt crystallization efficiency for p-cresol purification.The optimal crystallization conditions were determined:dynamic pulsed aeration at 90 L·h-1 and the cooling rate of 0.6-0.8 ℃·min-1,followed by sweating at 0.2-0.3 ℃·min-1 for 40 min.Results also demonstrate that the melt crystallization efficiency is sensitive to feed concentration,which highlights this technology for separation and purification of high purity products.展开更多
Biology is a rich source of great ideas that can inspire us to find successful ways to solve the challenging problems in engineering practices including those in the chemical industry. Bio-inspired chemical engineerin...Biology is a rich source of great ideas that can inspire us to find successful ways to solve the challenging problems in engineering practices including those in the chemical industry. Bio-inspired chemical engineering(Bio Ch E)may be recognized as a significant branch of chemical engineering. It may consist of, but not limited to, the following three aspects: 1) Chemical engineering principles and unit operations in biological systems; 2) Process engineering principles for producing existing or developing new chemical products through living ‘devices';and 3) Chemical engineering processes and equipment that are designed and constructed through mimicking(does not have to reproduce one hundred percent) the biological systems including their physical–chemical and mechanical structures to deliver uniquely beneficial performances. This may also include the bio-inspired sensors for process monitoring. In this paper, the above aspects are defined and discussed which establishes the scope of BioChE.展开更多
Culture is one of the important properties of language, and language can not be separated from society and culture. Every language is the reflection of culture with profound cultural connotations. Many experts and sch...Culture is one of the important properties of language, and language can not be separated from society and culture. Every language is the reflection of culture with profound cultural connotations. Many experts and scholars have generally agreed that intercultural communication competence is an important purpose of language learning. The process of learning English is the process to understand and master English cultural and knowledge, and mastery degree of English-speaking countries and cultural knowledge directly affects practical skills of one person.展开更多
Far from being equivalent to host the process, the vessels play an active role in the crystallization thanks to their differently shaped bottoms. It was clearly pointed out through a meticulous experimental research o...Far from being equivalent to host the process, the vessels play an active role in the crystallization thanks to their differently shaped bottoms. It was clearly pointed out through a meticulous experimental research on the batch crystallization of CAM (citric acid monohydrate) carried out in the years 1997-1998 by the author at the historic laboratories of"La Sapienza" University of Rome. Such pioneering M.Sc. thesis, supervised by Prof. Barbara Mazzarotta (Department of Chemical Engineering), was already summarized in an informative essay but, since the crystallization operating conditions to optimize were illustrated "collectively", it seemed necessary a further paper expounding uniquely the geometry effect. Our aim is to use all the data, collected and simulated, in order to show why the round-bottomed crystallizer performed better than the conical-bottomed one with the CAM from aqueous solutions, and why we should discard the flat-bottomed crystallizers.展开更多
At present, all aspects of China have entered the era of a rapid development, while the development speed of digital electronic technology is especially outstanding. This is a new way for China' s new personnel train...At present, all aspects of China have entered the era of a rapid development, while the development speed of digital electronic technology is especially outstanding. This is a new way for China' s new personnel training, and also proposes higher requirements on this type of personnel training institutions. In view of the demands of society and different majors on personnel, an enhancement to the standardized management of electronic laboratory operations becomes one of the important tasks for personnel training institutions. In this paper, how to practice the standardization management in an all-round way is discussed centered at college and university students' electronic laboratory.展开更多
Mango is a widely cultivated and consumed fruit in Brazil and one of the most important alternatives to take advantage of the production excess is dehydration. Therefore, this work aims at establishing better operatio...Mango is a widely cultivated and consumed fruit in Brazil and one of the most important alternatives to take advantage of the production excess is dehydration. Therefore, this work aims at establishing better operational conditions for "spray-drying" processes, in order to obtain the powder of mango pulp by means of a rotational central compounded planning, and also at carrying out the physicochemical characterization of both the integral mango pulp and the powder obtained from the operational conditions mentioned above. Both integral mango pulp and powder were analyzed as for the following physicochemical characteristics: humidity, pH, titratable acidity, soluble solids (~Brix), vitamin C and color--through parameters L*, a*, b* and h0, Chrome (C*) and color difference (AEL*a*b*). The experimental planning used presented significant differences at 5% of probability, showing that the model was adjusted to the data in accordance to F test, thus being possible to determine the best process conditions. In addition, the average results of the physicochemical parameters pointed out that the pulp used was in accordance with the patterns established by the quality and identity patterns for mango pulp. Moreover, it showed that the powder obtained had good physicochemical quality.展开更多
The ensemble technique has been widely used in numerical weather prediction and extended-range forecasting.Current approaches to evaluate the predictability using the ensemble technique can be divided into two major g...The ensemble technique has been widely used in numerical weather prediction and extended-range forecasting.Current approaches to evaluate the predictability using the ensemble technique can be divided into two major groups.One is dynamical,including generating Lyapunov vectors,bred vectors,and singular vectors,sampling the fastest error-growing directions of the phase space,and examining the dependence of prediction efficiency on ensemble size.The other is statistical,including distributional analysis and quantifying prediction utility by the Shannon entropy and the relative entropy.Currently,with simple models,one could choose as many ensembles as possible,with each ensemble containing a large number of members.When the forecast models become increasingly complicated,however,one would only be able to afford a small number of ensembles,each with limited number of members,thus sacrificing estimation accuracy of the forecast errors.To uncover connections between different information theoretic approaches and between dynamical and statistical approaches,we propose an (∈;T)-entropy and scale-dependent Lyapunov exponent——based general theoretical framework to quantify information loss in ensemble forecasting.More importantly,to tremendously expedite computations,reduce data storage,and improve forecasting accuracy,we propose a technique for constructing a large number of "pseudo" ensembles from one single solution or scalar dataset.This pseudo-ensemble technique appears to be applicable under rather general conditions,one important situation being that observational data are available but the exact dynamical model is unknown.展开更多
The seismic activities on the Earth can produce a disturbance of the electromagnetic field and particles in the ionosphere. The search coil magnetometer(SCM) mounted on China Seismo-Electromagnetic satellite(CSES) is ...The seismic activities on the Earth can produce a disturbance of the electromagnetic field and particles in the ionosphere. The search coil magnetometer(SCM) mounted on China Seismo-Electromagnetic satellite(CSES) is designed to measure the magnetic field fluctuation of low frequency electromagnetic waves in the frequency range of 10 Hz–20 k Hz. The SCM comprises a three-axis search coil sensor mounted on a 4.5 m boom and an electronic box inside satellite module. The sampling rate of the SCM is 51.2 k Hz and the time resolution of the power spectrum density(PSD) is 2 s. The frequency resolution is 12.5 Hz.There are three operation modes: survey, detailed survey and calibration. In the survey mode, the SCM can provide a PSD in the whole frequency range of 10 Hz–20 k Hz and wave forms in the low frequency range below 2 k Hz while in the detailed survey mode the SCM can provide both PSD and wave forms in the whole frequency range of 10 Hz–20 k Hz. The sensitivity of the SCM instrument is 5.0×10^(-4) n T Hz^(-1/2) at 10 Hz, 5.0×10^(–5) n T Hz^(-1/2) at 200 Hz, 3.4×10^(-5) n T Hz^(-1/2) at 2 k Hz and 1.1×10^(-4) n T Hz^(-1/2) at 20 k Hz. The telemetry rate is ~0.85 Mbps in the survey mode and ~3.0 Mbps in the detailed survey mode. The phase difference between three axes can be made generally with a precision of less than 1.0°. The dynamic range of the SCM instrument is over 100 d B. The orthogonality of three mechanical axes of search coil senor is better than 0.13°. The performance of SCM can satisfy the requirement of scientific objectives of CSES mission.展开更多
Small reactors have become a new hotspot of international nuclear energy research.The nuclear heating reactor(NHR)technology developed by Tsinghua University is an important multipurpose small reactor solution with fe...Small reactors have become a new hotspot of international nuclear energy research.The nuclear heating reactor(NHR)technology developed by Tsinghua University is an important multipurpose small reactor solution with features such as high integration,modular design and full power natural circulation.A new small reactor based on the existing NHR-200 reactor was developed by the Institute of Nuclear and New Energy Technology of Tsinghua University.A full-scale natural circulation test loop with the same operating parameters as the actual reactor was built in order to experimentally validate the natural circulation ability of the reactor primary loop and heat-transfer ability of fuel assemblies and heat exchangers.Corresponding results are given in detail,including parameter validation of the reactor primary loop,flow rules of the natural circulation and heat-transfer coefficients of heaters and heat exchangers,which can be directly used in the actual reactor as a reference for optimization design.Finally,a characteristic parameter k is proposed to represent the natural circulation ability of a system.By using the new data arrangement method in the form of parameter k,comprehensive experimental results of the natural circulation can be represented by a simple integrated expression.The work in this paper is of importance in broadening application fields and pushing forward commercialization of the NHR type reactors.展开更多
基金Supported by the National Basic Research Program of China (2009CB219905)Program for Changjiang Scholars and Innovative Research Team in University (IRT0936)Innovating Fund of Tianjin University
文摘Laboratory-scale experiments were carried out to evaluate the influences of operational parameters on the melt crystallization efficiency for p-cresol purification.The optimal crystallization conditions were determined:dynamic pulsed aeration at 90 L·h-1 and the cooling rate of 0.6-0.8 ℃·min-1,followed by sweating at 0.2-0.3 ℃·min-1 for 40 min.Results also demonstrate that the melt crystallization efficiency is sensitive to feed concentration,which highlights this technology for separation and purification of high purity products.
文摘Biology is a rich source of great ideas that can inspire us to find successful ways to solve the challenging problems in engineering practices including those in the chemical industry. Bio-inspired chemical engineering(Bio Ch E)may be recognized as a significant branch of chemical engineering. It may consist of, but not limited to, the following three aspects: 1) Chemical engineering principles and unit operations in biological systems; 2) Process engineering principles for producing existing or developing new chemical products through living ‘devices';and 3) Chemical engineering processes and equipment that are designed and constructed through mimicking(does not have to reproduce one hundred percent) the biological systems including their physical–chemical and mechanical structures to deliver uniquely beneficial performances. This may also include the bio-inspired sensors for process monitoring. In this paper, the above aspects are defined and discussed which establishes the scope of BioChE.
文摘Culture is one of the important properties of language, and language can not be separated from society and culture. Every language is the reflection of culture with profound cultural connotations. Many experts and scholars have generally agreed that intercultural communication competence is an important purpose of language learning. The process of learning English is the process to understand and master English cultural and knowledge, and mastery degree of English-speaking countries and cultural knowledge directly affects practical skills of one person.
文摘Far from being equivalent to host the process, the vessels play an active role in the crystallization thanks to their differently shaped bottoms. It was clearly pointed out through a meticulous experimental research on the batch crystallization of CAM (citric acid monohydrate) carried out in the years 1997-1998 by the author at the historic laboratories of"La Sapienza" University of Rome. Such pioneering M.Sc. thesis, supervised by Prof. Barbara Mazzarotta (Department of Chemical Engineering), was already summarized in an informative essay but, since the crystallization operating conditions to optimize were illustrated "collectively", it seemed necessary a further paper expounding uniquely the geometry effect. Our aim is to use all the data, collected and simulated, in order to show why the round-bottomed crystallizer performed better than the conical-bottomed one with the CAM from aqueous solutions, and why we should discard the flat-bottomed crystallizers.
文摘At present, all aspects of China have entered the era of a rapid development, while the development speed of digital electronic technology is especially outstanding. This is a new way for China' s new personnel training, and also proposes higher requirements on this type of personnel training institutions. In view of the demands of society and different majors on personnel, an enhancement to the standardized management of electronic laboratory operations becomes one of the important tasks for personnel training institutions. In this paper, how to practice the standardization management in an all-round way is discussed centered at college and university students' electronic laboratory.
文摘Mango is a widely cultivated and consumed fruit in Brazil and one of the most important alternatives to take advantage of the production excess is dehydration. Therefore, this work aims at establishing better operational conditions for "spray-drying" processes, in order to obtain the powder of mango pulp by means of a rotational central compounded planning, and also at carrying out the physicochemical characterization of both the integral mango pulp and the powder obtained from the operational conditions mentioned above. Both integral mango pulp and powder were analyzed as for the following physicochemical characteristics: humidity, pH, titratable acidity, soluble solids (~Brix), vitamin C and color--through parameters L*, a*, b* and h0, Chrome (C*) and color difference (AEL*a*b*). The experimental planning used presented significant differences at 5% of probability, showing that the model was adjusted to the data in accordance to F test, thus being possible to determine the best process conditions. In addition, the average results of the physicochemical parameters pointed out that the pulp used was in accordance with the patterns established by the quality and identity patterns for mango pulp. Moreover, it showed that the powder obtained had good physicochemical quality.
基金Project supported by the National Science Foundation (Nos.CMMI-0825311,CMMI-0826119)
文摘The ensemble technique has been widely used in numerical weather prediction and extended-range forecasting.Current approaches to evaluate the predictability using the ensemble technique can be divided into two major groups.One is dynamical,including generating Lyapunov vectors,bred vectors,and singular vectors,sampling the fastest error-growing directions of the phase space,and examining the dependence of prediction efficiency on ensemble size.The other is statistical,including distributional analysis and quantifying prediction utility by the Shannon entropy and the relative entropy.Currently,with simple models,one could choose as many ensembles as possible,with each ensemble containing a large number of members.When the forecast models become increasingly complicated,however,one would only be able to afford a small number of ensembles,each with limited number of members,thus sacrificing estimation accuracy of the forecast errors.To uncover connections between different information theoretic approaches and between dynamical and statistical approaches,we propose an (∈;T)-entropy and scale-dependent Lyapunov exponent——based general theoretical framework to quantify information loss in ensemble forecasting.More importantly,to tremendously expedite computations,reduce data storage,and improve forecasting accuracy,we propose a technique for constructing a large number of "pseudo" ensembles from one single solution or scalar dataset.This pseudo-ensemble technique appears to be applicable under rather general conditions,one important situation being that observational data are available but the exact dynamical model is unknown.
基金supported by the National Natural Science Foundation of China(Grant No.41431071)
文摘The seismic activities on the Earth can produce a disturbance of the electromagnetic field and particles in the ionosphere. The search coil magnetometer(SCM) mounted on China Seismo-Electromagnetic satellite(CSES) is designed to measure the magnetic field fluctuation of low frequency electromagnetic waves in the frequency range of 10 Hz–20 k Hz. The SCM comprises a three-axis search coil sensor mounted on a 4.5 m boom and an electronic box inside satellite module. The sampling rate of the SCM is 51.2 k Hz and the time resolution of the power spectrum density(PSD) is 2 s. The frequency resolution is 12.5 Hz.There are three operation modes: survey, detailed survey and calibration. In the survey mode, the SCM can provide a PSD in the whole frequency range of 10 Hz–20 k Hz and wave forms in the low frequency range below 2 k Hz while in the detailed survey mode the SCM can provide both PSD and wave forms in the whole frequency range of 10 Hz–20 k Hz. The sensitivity of the SCM instrument is 5.0×10^(-4) n T Hz^(-1/2) at 10 Hz, 5.0×10^(–5) n T Hz^(-1/2) at 200 Hz, 3.4×10^(-5) n T Hz^(-1/2) at 2 k Hz and 1.1×10^(-4) n T Hz^(-1/2) at 20 k Hz. The telemetry rate is ~0.85 Mbps in the survey mode and ~3.0 Mbps in the detailed survey mode. The phase difference between three axes can be made generally with a precision of less than 1.0°. The dynamic range of the SCM instrument is over 100 d B. The orthogonality of three mechanical axes of search coil senor is better than 0.13°. The performance of SCM can satisfy the requirement of scientific objectives of CSES mission.
基金supported by the National S&T Major Project(Grant No.ZX06901)the National Natural Science Foundation of China(Grant No.11072131)
文摘Small reactors have become a new hotspot of international nuclear energy research.The nuclear heating reactor(NHR)technology developed by Tsinghua University is an important multipurpose small reactor solution with features such as high integration,modular design and full power natural circulation.A new small reactor based on the existing NHR-200 reactor was developed by the Institute of Nuclear and New Energy Technology of Tsinghua University.A full-scale natural circulation test loop with the same operating parameters as the actual reactor was built in order to experimentally validate the natural circulation ability of the reactor primary loop and heat-transfer ability of fuel assemblies and heat exchangers.Corresponding results are given in detail,including parameter validation of the reactor primary loop,flow rules of the natural circulation and heat-transfer coefficients of heaters and heat exchangers,which can be directly used in the actual reactor as a reference for optimization design.Finally,a characteristic parameter k is proposed to represent the natural circulation ability of a system.By using the new data arrangement method in the form of parameter k,comprehensive experimental results of the natural circulation can be represented by a simple integrated expression.The work in this paper is of importance in broadening application fields and pushing forward commercialization of the NHR type reactors.