To reduce the number of digital predistortion coefficients, a step memory polynomial (SMP)predistorter is presented. The number of predistortion coefficients is decreased by adjusting the maximum nonlinear order for...To reduce the number of digital predistortion coefficients, a step memory polynomial (SMP)predistorter is presented. The number of predistortion coefficients is decreased by adjusting the maximum nonlinear order for different memory orders in the traditional memory polynomial (MP)predistorter. The proposed SNIP predistorter is identified by an offline learning structure on which the coefficients can be extracted directly from the sampled input and output of a PA. Simulation results show that the SMP predistorter is not tied to a particular PA model and is, therefore, robust. The effectiveness of the SMP predistorter is demonstrated by simulations and experiments on an MP model, a parallel Wiener model, a Wiener-Hammerstein model, a sparsedelay memory polynomial model and a real PA which is fabricated based on the Freescale LDMOSFET MRF21030. Compared with the traditional MP predistorter, the SMP predistorter can reduce the number of coefficients by 60%.展开更多
The selection of the truncation level (TL) and the control of boundary effect (BE) are critical in regional geomagnetic field models that are based on data fitting. We combine Taylor and Legendre polynomials to mo...The selection of the truncation level (TL) and the control of boundary effect (BE) are critical in regional geomagnetic field models that are based on data fitting. We combine Taylor and Legendre polynomials to model geomagnetic data over China's Mainland for years 1960, 1970, 1990, and 2000. To tackle the TL and BE problems, we first determine the range of TL by calculating the root-mean-square error (RMSE) of the models. Next, we determine the optimum TL using the Akaike information criterion (AIC) and the normalized root- mean-square error (NRMSE). We use the regional anomaly addition (RAA) and the uniform addition (UA) method to add supplementary point outside the national boundary, and find that the intensities of extreme points gradually decrease and stabilize. The UA method better controls BEs over China, whereas the RAA method does a better job at smaller scales. In summary, we rely on a three-step method to determine the optimum TL and propose criteria to determine the optimum number of supplementary points.展开更多
Based on broad literature search, the species, compositions, pharmacology, clinical applications, typical dietary and health taboo of tangerine pith were reviewed, to provide scientific materials for universal health ...Based on broad literature search, the species, compositions, pharmacology, clinical applications, typical dietary and health taboo of tangerine pith were reviewed, to provide scientific materials for universal health care.展开更多
AIM:To examine the links between quality of sleep and the severity of intestinal symptoms in irritable bow-el syndrome(IBS).METHODS:One hundred and forty-two outpatients(110female,32 male)who met the Rome Ⅲ criteria ...AIM:To examine the links between quality of sleep and the severity of intestinal symptoms in irritable bow-el syndrome(IBS).METHODS:One hundred and forty-two outpatients(110female,32 male)who met the Rome Ⅲ criteria for IBS with no psychiatric comorbidity were consecutively en-rolled in this study.Data on age,body mass index(BMI),and a set of life-habit variables were recorded,and IBS symptoms and sleep quality were evaluated using the questionnaires IBS Symptom Severity Score(IBS-SSS)and Pittsburgh Sleep Quality Index(PSQI).The associa-tion between severity of IBS and sleep disturbances was evaluated by comparing the global IBS-SSS and PSQI score(Pearson's correlation and Fisher's exact test)and then analyzing the individual items of the IBS-SSS and PSQI questionnaires by a unitary bowel-sleep model based on item response theory(IRT).RESULTS:IBS-SSS ranged from mild to severe(120-470).The global PSQI score ranged from 1 to 17(median 5),and 60 patients were found to be poor sleepers(PSQI>5).The correlation between the global IBS-SSS and PSQI score indicated a weak association(r=0.2 and 95% CI:-0.03 to 0.35,P<0.05),which becomes stronger using our unitary model.Indeed,the IBS and sleep disturbances severities,estimated as latent variables,resulted significantly high intra-subject cor-relation(posterior mean of r=0.45 and 95% CI:0.17 to 0.70,P<0.05).Moreover,the correlations between patient features(age,sex,BMI,daily coffee and alcohol intake)and IBS and sleep disturbances were also ana-lyzed through our unitary model.Age was a signif icant regressor,with patients≤50 years old showing more severe bowel disturbances(posterior mean=-0.38,P<0.05)and less severe sleep disturbances(posterior mean=0.49,P<0.05)than older patients.Higher daily coffee intake was correlated with a lower sever-ity of bowel disturbances(posterior mean=-0.31,P<0.05).Sex(female)and daily alcohol intake(modest)were correlated with less severe sleep disturbances.CONCLUSION:The unitary bowel-sleep model based on IRT revealed a strong positive correlation between the severity of IBS symptoms and sleep disturbances.展开更多
In order to capture the mechanism of roadway instability in deep mines, a new approach of Physically Finite Elemental Slab Assemblage (PFESA) is proposed in order to construct a large-scale physical model simulating t...In order to capture the mechanism of roadway instability in deep mines, a new approach of Physically Finite Elemental Slab Assemblage (PFESA) is proposed in order to construct a large-scale physical model simulating the geologically horizontal strata. We carried out physical modeling on the deformation and failure processes of roadways subjected to a plane loading scheme. Our laboratory tests were based on work which incorporated infrared (IR) detection, IR radiation temperature (IRT) statistics, image feature extraction and 2D Fourier transformation, from resulting thermographies. The IRT characterizes the mechanical responses from the roadway after loading with two stages, i.e., IRT evolving at higher levels corresponded to shallow mining (≤500 m) during which the roadway deformed gradually (referred to as the "steady deformation stage"); IRT evolving in a quasi-cyclical manner with multiple peaks corresponded to deep mining (800–2600 m), in which the failure mode for the roadway are dominated by breakage and collapse (called the "unsteady deformation stage"). The IR images and 2D Fourier spectra illustrate detailed information in terms of initiation, nucleation and coalescence of the damage to rock masses and the eventual failure of roadways subject to external loading.展开更多
Direct online measurement on product quality of industrial processes is difficult to be realized,which leads to a large number of unlabeled samples in modeling data.Therefore,it needs to employ semi-supervised learnin...Direct online measurement on product quality of industrial processes is difficult to be realized,which leads to a large number of unlabeled samples in modeling data.Therefore,it needs to employ semi-supervised learning(SSL)method to establish the soft sensor model of product quality.Considering the slow time-varying characteristic of industrial processes,the model parameters should be updated smoothly.According to this characteristic,this paper proposes an online adaptive semi-supervised learning algorithm based on random vector functional link network(RVFLN),denoted as OAS-RVFLN.By introducing a L2-fusion term that can be seen a weight deviation constraint,the proposed algorithm unifies the offline and online learning,and achieves smoothness of model parameter update.Empirical evaluations both on benchmark testing functions and datasets reveal that the proposed OAS-RVFLN can outperform the conventional methods in learning speed and accuracy.Finally,the OAS-RVFLN is applied to the coal dense medium separation process in coal industry to estimate the ash content of coal product,which further verifies its effectiveness and potential of industrial application.展开更多
This paper reports a five-year computer-mediated intercultural exchange project between Chinese and American university students that explores the use of various social media tools with WeChat application as the main ...This paper reports a five-year computer-mediated intercultural exchange project between Chinese and American university students that explores the use of various social media tools with WeChat application as the main medium in collaborative intercultural assignments. The study combines quantitative and qualitative approaches by using questionnaires and action research, to investigate how Chinese EFL and American CFL learners increase their intercultural communication competence by assessing their knowledge, awareness, attitudes, and skills of discovery and awareness. The findings reveal their changes and progress in the following variables: knowledge about the variety and subtlety of both the home and target cultures, a different worldview, and cultural study methods;awareness of the importance of differences and similarities between the home and target cultures, their negative reactions to these differences(e.g., fear, ridicule, disgust, feeling of superiority, etc.) and therefore, critical evaluation of the target and home cultures;attitudes from excitement or blind admiration of the target culture to confusion, anxiety or frustration about the cultural differences, later to toleration and appreciation of cultural differences, adaptation to the target culture, and eventually to openness and readiness to suspend disbelief about other cultures and belief about one’s own;skills to contrast the target culture with their own, to demonstrate a capacity to interact appropriately in a variety of different social situations in the target culture and resolve cross-cultural conflicts and misunderstandings. This research will serve as a valuable reference for computer-mediated intercultural communication teaching and open up new possibilities to extend classroom teaching by bridging the gap between second-hand knowledge and hands-on experience.展开更多
Based on engineering practices of Wuyang Coal Mine, we carried out X-ray diffract researches on No. 3 coal; and the rocks of its roof and floor by XRD meter, and simulated the interactive effect of the surrounding roc...Based on engineering practices of Wuyang Coal Mine, we carried out X-ray diffract researches on No. 3 coal; and the rocks of its roof and floor by XRD meter, and simulated the interactive effect of the surrounding rock deformation by FLAC2DS.0 numerical simulation software under the condition of different tunneling method of multimine roadway in parallel. The internal structures of the surrounding rocks of 76 belt roadway were monitored by borehole observation instruments: and then, we analyzed the reason of fhilure and deformation of surrounding rocks of several rise entry, and proposed the technical mea- sures for controlling interactive effect of several rise entry surrounding rock deformation at last. For the thickness seam rise roadway, two conclusions were drawn: one is that the co-deformation among roadway groups mainly reflect on that both shear failure and deformation in coal pillar among roadways have decreased the width of pillar core region and clamping action of coal pillar to roof strata, increased the actual span of roof strata, intensified the flexural failure of roof strata and prized the bed separation of roof deep rock strata. The other conclusion is that the factors controlling the interactive deformation among roadways is obvious when appropriate re-adjustment in construction sequence of the tunneling of multimine parallel roadways because the construction sequence among roadways also has great effects on deformation of the surrounding rock in roadway.展开更多
A modified polynomial preserving gradient recovery technique is proposed. Unlike the polynomial preserving gradient recovery technique,the gradient recovered with the modified polynomial preserving recovery(MPPR) is c...A modified polynomial preserving gradient recovery technique is proposed. Unlike the polynomial preserving gradient recovery technique,the gradient recovered with the modified polynomial preserving recovery(MPPR) is constructed element-wise, and it is discontinuous across the interior edges.One advantage of the MPPR technique is that the implementation is easier when adaptive meshes are involved.Superconvergence results of the gradient recovered with MPPR are proved for finite element methods for elliptic boundary problems and eigenvalue problems under adaptive meshes. The MPPR is applied to adaptive finite element methods to construct asymptotic exact a posteriori error estimates.Numerical tests are provided to examine the theoretical results and the effectiveness of the adaptive finite element algorithms.展开更多
Construction companies face threats from competition and must be able to adjust to modem technology and changes in customer expectations. These issues require efficient risk management techniques. The success of const...Construction companies face threats from competition and must be able to adjust to modem technology and changes in customer expectations. These issues require efficient risk management techniques. The success of construction companies running projects in international markets depends on how the risks arise from the host country conditions as well as the project specific risk factors. Successful management of risks requires identification of risks, construction of a risk model which can be used to assess the magnitude of risks, and implementation of response strategies so that an acceptable risk-return balance can be achieved. The project success usually depends on the combination of all risks, response strategies used to mitigate risks, and a company's ability to manage them. There exists a need to develop risk models containing the risks of doing business in international markets and factors that affect manageability of these risks. One of the market's critical challenges is scheduled management and the understanding and application of program management. This paper uses systematic risk identification, classification and analysis, and measurement and response methodologies to help international contractors quantify the risks of project development and accomplishment.展开更多
Aims of this paper are to improve ADI differential quadrature method (ADI-DQM) based on Bernstein polynomials and add a new application to the differential quadrature method. By using the new methodology, the numeri...Aims of this paper are to improve ADI differential quadrature method (ADI-DQM) based on Bernstein polynomials and add a new application to the differential quadrature method. By using the new methodology, the numerical solutions of the governing equations of unsteady two-dimensional flow of a polytropic gas are investigated. The numerical results reveal that the new technique is very effective and gives high accuracy, good convergence and reasonable stability.展开更多
This paper studies the technics of reducing item exposure by utilizing automatic item generation methods. Known test item calibration method uses item parameter estimation with the statistical data, collected during e...This paper studies the technics of reducing item exposure by utilizing automatic item generation methods. Known test item calibration method uses item parameter estimation with the statistical data, collected during examinees prior testing. Disadvantage of the mentioned item calibration method is the item exposure; when test items become familiar to the examinees. To reduce the item exposure, automatic item generation method is used, where item models are being constructed based on already calibrated test items without losing already estimated item parameters. A technic of item model extraction method from the already calibrated and therefore exposed test items described, which can be used by the test item development specialists to integrate automatic item generation principles with the existing testing applications.展开更多
Based on the engineering project on a small coal pillar of 12,521 working face roadway in Xieqiao Coalmine, data regarding surface displacements of the coal pillar, deep displacements and mining stress have been colle...Based on the engineering project on a small coal pillar of 12,521 working face roadway in Xieqiao Coalmine, data regarding surface displacements of the coal pillar, deep displacements and mining stress have been collected and analyzed. The results show that macroscopic transverse fractures of the inner coal pillar are developed within 2–4 m of the roadway surface, which is located outside the coal pillar anchorage zone. There is a displacement of 530 mm at the monitoring point in the 6 m deep zone of the pillar. Transfer of the fracture zone is found in a small coal pillar and the fractures within 3–4 m of the coal-rock zone from the roadway surface undergo propagation and closure of cracks which means this fracture zone is transferred from 3–4 m outside the roadway to only 2–3 m from the roadway surface. In the monitoring zone, vertical and horizontal stresses increase with a feature that shows that acceleration in the deep zone of the pillar is greater than that in the shallow zone. Furthermore, the acceleration of vertical stress is also greater than that of horizontal stress with a peak value in the 4 m zone.The research findings provide a reference for the regulation of a reasonable width of coal pillar in coalmines and optimal control design of surrounding rock.展开更多
The central composite design in the modeling and optimization of catalytic dehydration of ethanol to ethylene was performed to improve the ethylene yield.A total of 20 experiments at random were conducted to investiga...The central composite design in the modeling and optimization of catalytic dehydration of ethanol to ethylene was performed to improve the ethylene yield.A total of 20 experiments at random were conducted to investigate the effect of reaction temperature,Si/Al ratios of H-ZSM-5 catalyst and liquid hourly space velocity(LHSV) on the ethylene yield.The results show that the relationship between ethylene yield and the three significant independent variables can be approximated by a nonlinear polynomial model,with R-squared of 99.9%and adjusted R-squared of 99.8%.The maximal response for ethylene yield is 93.4%under the optimal condition of 328 ℃,Si/Al ratio 85,and LHSV 3.8 h-1.展开更多
Internal quality audits are a key activity in the quality management ofoil projects.Quality management aims at meeting project quality requirements,coordinatingproject progress,assisting in controlling project costs,a...Internal quality audits are a key activity in the quality management ofoil projects.Quality management aims at meeting project quality requirements,coordinatingproject progress,assisting in controlling project costs,and realizing continuousimprovement in project quality management.展开更多
Based on the study of supply chain(SC) and SC optimization in engineering projects, a mixed integer nonlinear programming(MINLP) optimization model is developed to minimize the total SC cost for international petroche...Based on the study of supply chain(SC) and SC optimization in engineering projects, a mixed integer nonlinear programming(MINLP) optimization model is developed to minimize the total SC cost for international petrochemical engineering projects. A steam cracking project is selected and analyzed, from which typical SC characteristics in international engineering projects in the area of petrochemical industry are summarized. The MINLP model is therefore developed and applied to projects with detailed data. The optimization results are analyzed and compared by the MINLP model, indicating that they are appropriate to SC management practice in engineering projects, and are consistent with the optimal priceeffective strategy in procurement. As a result, the model could provide useful guidance to SC optimization of international engineering projects in petrochemical industry, and improve SC management by selecting more reliable and qualified partner enterprises in SC for the project.展开更多
Projects delay and cost overrun have become general facts in the construction industry. Project cost risk analysis considers the different costs associated with a project and focuses on the uncertainties and risks tha...Projects delay and cost overrun have become general facts in the construction industry. Project cost risk analysis considers the different costs associated with a project and focuses on the uncertainties and risks that may affect these costs. An implementation of PRM (project risk management) process on regional construction project has been carried out to maximize the likelihood of project meeting its objectives within its constraints. Qualitative and quantitative risk analyses have been carried out. The qualitative analysis is presented in a table that shows top ranked risks in Libyan construction projects based on probability-impact grid technique. In quantitative risk analyses, Mont Carlo simulation technique has been conducted to quantify and evaluate the overall level of risk exposure associated with the project completion cost. A project simulation uses a model that translates cost uncertainties into their potential impact on project objectives. A frequency curve model that represents simulation results of project completion costs has been constructed. The frequency curve model shows all possible outcomes of expected project cost at different probabilities. Project manager or decision maker can select the appropriate project budget. If a probability of 0.95 confident project budget is selected that means cost overrun risk can be minimized to a probability of 0.05. It is very helpful for project manager to take decisions based on information that shows project completion cost and its associated probability rather than usin single information of estimated cost.展开更多
Interactive digital television is at early stage as regards the interface design, especially in business transactions (t-commerce). Current attempts to transpose the problem related to linearity of narrative and tem...Interactive digital television is at early stage as regards the interface design, especially in business transactions (t-commerce). Current attempts to transpose the problem related to linearity of narrative and temporal flows and audiovisual content obstruction by the interactive layer, although pointing out design perspectives--in addition to the structural and visual web patterns--are still insufficient as regards the design of interfaces connected and converged for t-commerce applications. This article considers that these problems arise from the structural basis that support television scripts and streamings. In this sense, this article proposes the hybridization between the linear model, inherited from analogue condition, and nonlinear model, intrinsic to digital media, as a methodological strategy aiming to strength the creation of interactive audiovisual content connected and convergent for this context.展开更多
This paper, on the basis of the author realizing the skill evaluation system based on real environment, discusses several commonly used parameter estimation methods based on item response theory ( IRT ) and analyzes...This paper, on the basis of the author realizing the skill evaluation system based on real environment, discusses several commonly used parameter estimation methods based on item response theory ( IRT ) and analyzes the advantages and disadvantages of each estimation method and their respective application fields. Also, it expounds the research theory and design process of skill adaptive evaluation system based on real environment and the innovation of the system.展开更多
We analytically derive the solutions for electromagnetic fields of electric current dipole moment, which is placed in the exterior of the spherical homogeneous conductor, and is pointed along the radial direction. The...We analytically derive the solutions for electromagnetic fields of electric current dipole moment, which is placed in the exterior of the spherical homogeneous conductor, and is pointed along the radial direction. The dipole moment is driven in the low frequency f = 1 kHz and high frequency f = 1 GHz regimes. The electrical properties of the conductor are appropriately chosen in each frequency. Electromagnetic fields are rigorously formulated at an arbitrary point in a spherical geometry, in which the magnetic vector potential is straightforwardly given by the Biot- Savart formula, and the scalar potential is expanded with the Legendre polynomials, taking into account the appropriate boundary conditions at the spherical surface of the conductor. The induced electric fields are numerically calculated along the several paths in the low and high frequeny excitation. The self-consistent solutions obtained in this work will be of much importance in a wide region of electromagnetic induction problems.展开更多
基金The National High Technology Research and Development Program of China (863 Program) (No.2008AA01Z211)the Project of Industry-Academia-Research Demonstration Base of Education Ministry of Guangdong Province (No.2007B090200012)
文摘To reduce the number of digital predistortion coefficients, a step memory polynomial (SMP)predistorter is presented. The number of predistortion coefficients is decreased by adjusting the maximum nonlinear order for different memory orders in the traditional memory polynomial (MP)predistorter. The proposed SNIP predistorter is identified by an offline learning structure on which the coefficients can be extracted directly from the sampled input and output of a PA. Simulation results show that the SMP predistorter is not tied to a particular PA model and is, therefore, robust. The effectiveness of the SMP predistorter is demonstrated by simulations and experiments on an MP model, a parallel Wiener model, a Wiener-Hammerstein model, a sparsedelay memory polynomial model and a real PA which is fabricated based on the Freescale LDMOSFET MRF21030. Compared with the traditional MP predistorter, the SMP predistorter can reduce the number of coefficients by 60%.
基金supported by the National Natural Science Foundation of China(Grant Nos.41404053 and 41174165)Special Project for Meteo-Scientific Research in the Public Interest(Grant No.GYHY201306073)Natural Science Foundation of Higher Education Institutions of Jiangsu Province,China(Grant No.14KJB170012)
文摘The selection of the truncation level (TL) and the control of boundary effect (BE) are critical in regional geomagnetic field models that are based on data fitting. We combine Taylor and Legendre polynomials to model geomagnetic data over China's Mainland for years 1960, 1970, 1990, and 2000. To tackle the TL and BE problems, we first determine the range of TL by calculating the root-mean-square error (RMSE) of the models. Next, we determine the optimum TL using the Akaike information criterion (AIC) and the normalized root- mean-square error (NRMSE). We use the regional anomaly addition (RAA) and the uniform addition (UA) method to add supplementary point outside the national boundary, and find that the intensities of extreme points gradually decrease and stabilize. The UA method better controls BEs over China, whereas the RAA method does a better job at smaller scales. In summary, we rely on a three-step method to determine the optimum TL and propose criteria to determine the optimum number of supplementary points.
基金Supported by the Key Laboratory of Resource Biology and Biotechnology in Western China of Ministry of Education(KH09030)the Special Fund for the Science and Technology of Science and Technology Department of Tibet Autonomous Region(20091012)the Scientific Research Program Funded by Shaanxi Provincial Education Department(2010JK862)~~
文摘Based on broad literature search, the species, compositions, pharmacology, clinical applications, typical dietary and health taboo of tangerine pith were reviewed, to provide scientific materials for universal health care.
文摘AIM:To examine the links between quality of sleep and the severity of intestinal symptoms in irritable bow-el syndrome(IBS).METHODS:One hundred and forty-two outpatients(110female,32 male)who met the Rome Ⅲ criteria for IBS with no psychiatric comorbidity were consecutively en-rolled in this study.Data on age,body mass index(BMI),and a set of life-habit variables were recorded,and IBS symptoms and sleep quality were evaluated using the questionnaires IBS Symptom Severity Score(IBS-SSS)and Pittsburgh Sleep Quality Index(PSQI).The associa-tion between severity of IBS and sleep disturbances was evaluated by comparing the global IBS-SSS and PSQI score(Pearson's correlation and Fisher's exact test)and then analyzing the individual items of the IBS-SSS and PSQI questionnaires by a unitary bowel-sleep model based on item response theory(IRT).RESULTS:IBS-SSS ranged from mild to severe(120-470).The global PSQI score ranged from 1 to 17(median 5),and 60 patients were found to be poor sleepers(PSQI>5).The correlation between the global IBS-SSS and PSQI score indicated a weak association(r=0.2 and 95% CI:-0.03 to 0.35,P<0.05),which becomes stronger using our unitary model.Indeed,the IBS and sleep disturbances severities,estimated as latent variables,resulted significantly high intra-subject cor-relation(posterior mean of r=0.45 and 95% CI:0.17 to 0.70,P<0.05).Moreover,the correlations between patient features(age,sex,BMI,daily coffee and alcohol intake)and IBS and sleep disturbances were also ana-lyzed through our unitary model.Age was a signif icant regressor,with patients≤50 years old showing more severe bowel disturbances(posterior mean=-0.38,P<0.05)and less severe sleep disturbances(posterior mean=0.49,P<0.05)than older patients.Higher daily coffee intake was correlated with a lower sever-ity of bowel disturbances(posterior mean=-0.31,P<0.05).Sex(female)and daily alcohol intake(modest)were correlated with less severe sleep disturbances.CONCLUSION:The unitary bowel-sleep model based on IRT revealed a strong positive correlation between the severity of IBS symptoms and sleep disturbances.
基金Projects 2006CB202200 supported by the Special Funds for the Major State Basic Research ProjectIRT0656 by the Innovative Team Development Project of the State Educational Ministry of China
文摘In order to capture the mechanism of roadway instability in deep mines, a new approach of Physically Finite Elemental Slab Assemblage (PFESA) is proposed in order to construct a large-scale physical model simulating the geologically horizontal strata. We carried out physical modeling on the deformation and failure processes of roadways subjected to a plane loading scheme. Our laboratory tests were based on work which incorporated infrared (IR) detection, IR radiation temperature (IRT) statistics, image feature extraction and 2D Fourier transformation, from resulting thermographies. The IRT characterizes the mechanical responses from the roadway after loading with two stages, i.e., IRT evolving at higher levels corresponded to shallow mining (≤500 m) during which the roadway deformed gradually (referred to as the "steady deformation stage"); IRT evolving in a quasi-cyclical manner with multiple peaks corresponded to deep mining (800–2600 m), in which the failure mode for the roadway are dominated by breakage and collapse (called the "unsteady deformation stage"). The IR images and 2D Fourier spectra illustrate detailed information in terms of initiation, nucleation and coalescence of the damage to rock masses and the eventual failure of roadways subject to external loading.
基金Projects(61603393,61973306)supported in part by the National Natural Science Foundation of ChinaProject(BK20160275)supported by the Natural Science Foundation of Jiangsu Province,China+1 种基金Projects(2015M581885,2018T110571)supported by the Postdoctoral Science Foundation of ChinaProject(PAL-N201706)supported by the Open Project Foundation of State Key Laboratory of Synthetical Automation for Process Industries of Northeastern University,China
文摘Direct online measurement on product quality of industrial processes is difficult to be realized,which leads to a large number of unlabeled samples in modeling data.Therefore,it needs to employ semi-supervised learning(SSL)method to establish the soft sensor model of product quality.Considering the slow time-varying characteristic of industrial processes,the model parameters should be updated smoothly.According to this characteristic,this paper proposes an online adaptive semi-supervised learning algorithm based on random vector functional link network(RVFLN),denoted as OAS-RVFLN.By introducing a L2-fusion term that can be seen a weight deviation constraint,the proposed algorithm unifies the offline and online learning,and achieves smoothness of model parameter update.Empirical evaluations both on benchmark testing functions and datasets reveal that the proposed OAS-RVFLN can outperform the conventional methods in learning speed and accuracy.Finally,the OAS-RVFLN is applied to the coal dense medium separation process in coal industry to estimate the ash content of coal product,which further verifies its effectiveness and potential of industrial application.
文摘This paper reports a five-year computer-mediated intercultural exchange project between Chinese and American university students that explores the use of various social media tools with WeChat application as the main medium in collaborative intercultural assignments. The study combines quantitative and qualitative approaches by using questionnaires and action research, to investigate how Chinese EFL and American CFL learners increase their intercultural communication competence by assessing their knowledge, awareness, attitudes, and skills of discovery and awareness. The findings reveal their changes and progress in the following variables: knowledge about the variety and subtlety of both the home and target cultures, a different worldview, and cultural study methods;awareness of the importance of differences and similarities between the home and target cultures, their negative reactions to these differences(e.g., fear, ridicule, disgust, feeling of superiority, etc.) and therefore, critical evaluation of the target and home cultures;attitudes from excitement or blind admiration of the target culture to confusion, anxiety or frustration about the cultural differences, later to toleration and appreciation of cultural differences, adaptation to the target culture, and eventually to openness and readiness to suspend disbelief about other cultures and belief about one’s own;skills to contrast the target culture with their own, to demonstrate a capacity to interact appropriately in a variety of different social situations in the target culture and resolve cross-cultural conflicts and misunderstandings. This research will serve as a valuable reference for computer-mediated intercultural communication teaching and open up new possibilities to extend classroom teaching by bridging the gap between second-hand knowledge and hands-on experience.
基金provided by the National Natural Science Foundation of China (No. 50674046)the Open Foundation of Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal Mines of China (No. 200803)
文摘Based on engineering practices of Wuyang Coal Mine, we carried out X-ray diffract researches on No. 3 coal; and the rocks of its roof and floor by XRD meter, and simulated the interactive effect of the surrounding rock deformation by FLAC2DS.0 numerical simulation software under the condition of different tunneling method of multimine roadway in parallel. The internal structures of the surrounding rocks of 76 belt roadway were monitored by borehole observation instruments: and then, we analyzed the reason of fhilure and deformation of surrounding rocks of several rise entry, and proposed the technical mea- sures for controlling interactive effect of several rise entry surrounding rock deformation at last. For the thickness seam rise roadway, two conclusions were drawn: one is that the co-deformation among roadway groups mainly reflect on that both shear failure and deformation in coal pillar among roadways have decreased the width of pillar core region and clamping action of coal pillar to roof strata, increased the actual span of roof strata, intensified the flexural failure of roof strata and prized the bed separation of roof deep rock strata. The other conclusion is that the factors controlling the interactive deformation among roadways is obvious when appropriate re-adjustment in construction sequence of the tunneling of multimine parallel roadways because the construction sequence among roadways also has great effects on deformation of the surrounding rock in roadway.
基金supported by the national basic research program of China under grant 2005CB321701the program for the new century outstanding talents in universities of China.
文摘A modified polynomial preserving gradient recovery technique is proposed. Unlike the polynomial preserving gradient recovery technique,the gradient recovered with the modified polynomial preserving recovery(MPPR) is constructed element-wise, and it is discontinuous across the interior edges.One advantage of the MPPR technique is that the implementation is easier when adaptive meshes are involved.Superconvergence results of the gradient recovered with MPPR are proved for finite element methods for elliptic boundary problems and eigenvalue problems under adaptive meshes. The MPPR is applied to adaptive finite element methods to construct asymptotic exact a posteriori error estimates.Numerical tests are provided to examine the theoretical results and the effectiveness of the adaptive finite element algorithms.
文摘Construction companies face threats from competition and must be able to adjust to modem technology and changes in customer expectations. These issues require efficient risk management techniques. The success of construction companies running projects in international markets depends on how the risks arise from the host country conditions as well as the project specific risk factors. Successful management of risks requires identification of risks, construction of a risk model which can be used to assess the magnitude of risks, and implementation of response strategies so that an acceptable risk-return balance can be achieved. The project success usually depends on the combination of all risks, response strategies used to mitigate risks, and a company's ability to manage them. There exists a need to develop risk models containing the risks of doing business in international markets and factors that affect manageability of these risks. One of the market's critical challenges is scheduled management and the understanding and application of program management. This paper uses systematic risk identification, classification and analysis, and measurement and response methodologies to help international contractors quantify the risks of project development and accomplishment.
文摘Aims of this paper are to improve ADI differential quadrature method (ADI-DQM) based on Bernstein polynomials and add a new application to the differential quadrature method. By using the new methodology, the numerical solutions of the governing equations of unsteady two-dimensional flow of a polytropic gas are investigated. The numerical results reveal that the new technique is very effective and gives high accuracy, good convergence and reasonable stability.
文摘This paper studies the technics of reducing item exposure by utilizing automatic item generation methods. Known test item calibration method uses item parameter estimation with the statistical data, collected during examinees prior testing. Disadvantage of the mentioned item calibration method is the item exposure; when test items become familiar to the examinees. To reduce the item exposure, automatic item generation method is used, where item models are being constructed based on already calibrated test items without losing already estimated item parameters. A technic of item model extraction method from the already calibrated and therefore exposed test items described, which can be used by the test item development specialists to integrate automatic item generation principles with the existing testing applications.
基金the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT1084)the Open Fund of Hunan provincial Key Laboratory for Safe Mining Technology of Coal Mine (No. 201103)the National Natural Science Foundation of China (No. 51274193)
文摘Based on the engineering project on a small coal pillar of 12,521 working face roadway in Xieqiao Coalmine, data regarding surface displacements of the coal pillar, deep displacements and mining stress have been collected and analyzed. The results show that macroscopic transverse fractures of the inner coal pillar are developed within 2–4 m of the roadway surface, which is located outside the coal pillar anchorage zone. There is a displacement of 530 mm at the monitoring point in the 6 m deep zone of the pillar. Transfer of the fracture zone is found in a small coal pillar and the fractures within 3–4 m of the coal-rock zone from the roadway surface undergo propagation and closure of cracks which means this fracture zone is transferred from 3–4 m outside the roadway to only 2–3 m from the roadway surface. In the monitoring zone, vertical and horizontal stresses increase with a feature that shows that acceleration in the deep zone of the pillar is greater than that in the shallow zone. Furthermore, the acceleration of vertical stress is also greater than that of horizontal stress with a peak value in the 4 m zone.The research findings provide a reference for the regulation of a reasonable width of coal pillar in coalmines and optimal control design of surrounding rock.
基金Supported by National Natural Science Foundation of China(No.70671072)
文摘The central composite design in the modeling and optimization of catalytic dehydration of ethanol to ethylene was performed to improve the ethylene yield.A total of 20 experiments at random were conducted to investigate the effect of reaction temperature,Si/Al ratios of H-ZSM-5 catalyst and liquid hourly space velocity(LHSV) on the ethylene yield.The results show that the relationship between ethylene yield and the three significant independent variables can be approximated by a nonlinear polynomial model,with R-squared of 99.9%and adjusted R-squared of 99.8%.The maximal response for ethylene yield is 93.4%under the optimal condition of 328 ℃,Si/Al ratio 85,and LHSV 3.8 h-1.
文摘Internal quality audits are a key activity in the quality management ofoil projects.Quality management aims at meeting project quality requirements,coordinatingproject progress,assisting in controlling project costs,and realizing continuousimprovement in project quality management.
文摘Based on the study of supply chain(SC) and SC optimization in engineering projects, a mixed integer nonlinear programming(MINLP) optimization model is developed to minimize the total SC cost for international petrochemical engineering projects. A steam cracking project is selected and analyzed, from which typical SC characteristics in international engineering projects in the area of petrochemical industry are summarized. The MINLP model is therefore developed and applied to projects with detailed data. The optimization results are analyzed and compared by the MINLP model, indicating that they are appropriate to SC management practice in engineering projects, and are consistent with the optimal priceeffective strategy in procurement. As a result, the model could provide useful guidance to SC optimization of international engineering projects in petrochemical industry, and improve SC management by selecting more reliable and qualified partner enterprises in SC for the project.
文摘Projects delay and cost overrun have become general facts in the construction industry. Project cost risk analysis considers the different costs associated with a project and focuses on the uncertainties and risks that may affect these costs. An implementation of PRM (project risk management) process on regional construction project has been carried out to maximize the likelihood of project meeting its objectives within its constraints. Qualitative and quantitative risk analyses have been carried out. The qualitative analysis is presented in a table that shows top ranked risks in Libyan construction projects based on probability-impact grid technique. In quantitative risk analyses, Mont Carlo simulation technique has been conducted to quantify and evaluate the overall level of risk exposure associated with the project completion cost. A project simulation uses a model that translates cost uncertainties into their potential impact on project objectives. A frequency curve model that represents simulation results of project completion costs has been constructed. The frequency curve model shows all possible outcomes of expected project cost at different probabilities. Project manager or decision maker can select the appropriate project budget. If a probability of 0.95 confident project budget is selected that means cost overrun risk can be minimized to a probability of 0.05. It is very helpful for project manager to take decisions based on information that shows project completion cost and its associated probability rather than usin single information of estimated cost.
文摘Interactive digital television is at early stage as regards the interface design, especially in business transactions (t-commerce). Current attempts to transpose the problem related to linearity of narrative and temporal flows and audiovisual content obstruction by the interactive layer, although pointing out design perspectives--in addition to the structural and visual web patterns--are still insufficient as regards the design of interfaces connected and converged for t-commerce applications. This article considers that these problems arise from the structural basis that support television scripts and streamings. In this sense, this article proposes the hybridization between the linear model, inherited from analogue condition, and nonlinear model, intrinsic to digital media, as a methodological strategy aiming to strength the creation of interactive audiovisual content connected and convergent for this context.
文摘This paper, on the basis of the author realizing the skill evaluation system based on real environment, discusses several commonly used parameter estimation methods based on item response theory ( IRT ) and analyzes the advantages and disadvantages of each estimation method and their respective application fields. Also, it expounds the research theory and design process of skill adaptive evaluation system based on real environment and the innovation of the system.
基金Supported by the Program for Promotion of Fundamental Studies in Health Sciences of the National Institute of Biomedical Innovation,NIBIO
文摘We analytically derive the solutions for electromagnetic fields of electric current dipole moment, which is placed in the exterior of the spherical homogeneous conductor, and is pointed along the radial direction. The dipole moment is driven in the low frequency f = 1 kHz and high frequency f = 1 GHz regimes. The electrical properties of the conductor are appropriately chosen in each frequency. Electromagnetic fields are rigorously formulated at an arbitrary point in a spherical geometry, in which the magnetic vector potential is straightforwardly given by the Biot- Savart formula, and the scalar potential is expanded with the Legendre polynomials, taking into account the appropriate boundary conditions at the spherical surface of the conductor. The induced electric fields are numerically calculated along the several paths in the low and high frequeny excitation. The self-consistent solutions obtained in this work will be of much importance in a wide region of electromagnetic induction problems.