Particle size distributions and concentrations above radiators in indoor environments: Exploratory results from Xi`an, China

Xi Chen,Angui Li 대한환경공학회 2015 Environmental Engineering Research Vol.20 No.3

Particulate matter in indoor environments has caused public concerns in recent years. The objective of this research is to explore the influence of radiators on particle size distributions and concentrations. The particle size distributions as well as concentrations above radiators and in the adjacent indoor air are monitored in forty-two indoor environments in Xi’an, China. The temperatures, relative humidity and air velocities are also measured. The particle size distributions above radiators at ten locations are analyzed. The results show that the functional difference of indoor environments has little impact on the particle size distributions above radiators. Then the effects of the environmental parameters (particle concentrations in the adjacent indoor air, temperatures, relative humidities and air velocities) on particle concentrations above radiators are assessed by applying multiple linear regression analysis. Three multiple linear regression models are established to predict the concentrations of PM10, PM2.5 and PM1 above radiators.

Efficient VaR and CVaR Measurement via Stochastic Kriging

Chen, Xi,Kim, Kyoung-Kuk Institute for Operations Research and the Manageme 2016 INFORMS journal on computing Vol.28 No.4

<P>In this paper, stochastic kriging (SK) is considered as a metamodeling tool to capture risk-related properties of complex stochastic system outputs. To better assess the tail behavior of the underlying distribution of a system output, we specifically focus on global prediction of value-at-risk and conditional value-at-risk. Going beyond the standard SK framework intended for metamodeling of mean response surfaces, we rethink the original formulation to allow for the flexibility of utilizing different estimation methods for metamodel construction. The resulting impact on the predictive performance of SK is examined in detail. In parallel with the study by Chen et al. [Chen X, Ankenman BE, Nelson BL (2013) Enhancing stochastic kriging metamodels with gradient estimators. Oper. Res. 61(2): 512-528], we further consider the situation in which noisy gradient information can be incorporated into SK metamodel construction and prediction. The theoretical results are illustrated by two numerical examples.</P>

Research Optimization of the Management of New Product Development Projects: the case of Lenovo

Chen Xi,Wang Xinyu,Li Hao 한중경제문화학회 2024 한중경제문화연구 Vol.25 No.-

In recent years, electronic products have played an increasingly important role in modern society and have penetrated into people’s life and work. With the continuous development of technology and the increasing demand for convenience and innovation, the functions and performance of electronic products continue to improve. However, the intensification of market competition and the rapid advancement of technological progress have brought many challenges and opportunities to the field of electronic products. This paper takes the new product development project management process of Lenovo Company as the research object, adopts investigation analysis method, literature analysis method and project management theory and gateway development management theory to deeply analyze the existing problems in the new product development project management of Lenovo Company, such as: The new product development cycle is long, the new product development cost is over budget, the new product development project organization and coordination ability is weak, and the project monitoring and feedback are not timely. The causes of these problems are analyzed. In view of the existing problems, this paper makes an in-depth study of the relevant theories of project management and new product development, and puts forward an optimization scheme suitable for the improvement of the new product development project management of Lenovo Company. It means adopting agile development scheme, establishing project development cost control point, optimizing organizational structure, and establishing perfect project management supervision and feedback mechanism. Finally, based on the current situation of Lenovo ‘s new product development, this paper proposes the guarantee measures for the smooth implementation of the new product development project management optimization plan, namely, talent guarantee, development and innovation awareness, risk control awareness, and management awareness in strengthening cultural construction, so as to ensure the smooth implementation of new product development project management.

A FORWARD-BACKWARD VQ CLUSTERING ALGORITHM FOR MULTISYLLABLE WORD RECOGNITION

Xi Xian Chen,Chang Nian Cai 대한전자공학회 1989 JTC-CSCC : Joint Technical Conference on Circuits Vol.- No.-

Release Kinetics of Tocopheroland Quercetin fromBinary Antioxidant Controlled-Release Packaging Films

Chen, Xi,Lee, Dong Sun,Zhu, Xuntao,Yam, Kit L. American Chemical Society 2012 Journal of agricultural and food chemistry Vol.60 No.13

<P>This paper investigated the feasibility of manipulatingpackagingpolymers with various degrees of hydrophobicity to release two antioxidants,tocopherol and quercetin, at rates suitable for long-term inhibitionof lipid oxidation in food. For example, one antioxidant can be releasedat a fast rate to provide short-term/intermediate protection, whereasthe other antioxidant can be released at a slower rate to provideintermediate/long-term protection of lipid oxidation. Controlled-releasepackaging films containing tocopherol and quercetin were producedusing ethylene vinyl alcohol (EVOH), ethylene vinyl acetate (EVA),low-density polyethylene (LDPE), and polypropylene (PP) polymers;the release of these antioxidants to 95% ethanol (a fatty food simulant)was measured using UV–vis spectrophotometry, and Fickian diffusionmodels with appropriate initial and boundary conditions were usedto fit the data. For films containing only quercetin, the resultsshow that the release of quercetin was much faster but lasted fora much shorter time for hydrophilic polymers (EVOH and EVA) than forhydrophobic polymers (LDPE and PP). For binary antioxidant films containingtocopherol and quercetin, the results show that tocopherol releasedmore rapidly but for a shorter period of time than quercetin in LDPEand EVOH films, and the difference is more pronounced for LDPE filmsthan EVOH films. The results also show the presence of tocopherolcan accelerate the release of quercetin. Although none of the filmsproduced is acceptable for long-term lipid oxidation inhibition, thestudy provides encouraging results suggesting that acceptable filmsmay be produced in the future using polymer blend films.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2012/jafcau.2012.60.issue-13/jf2045813/production/images/medium/jf-2011-045813_0006.gif'></P>

CircFam190a: a critical positive regulator of osteoclast differentiation via enhancement of the AKT1/HSP90β complex

Chen Kun,Chen Xi,Lang Chuandong,Yuan Xingshi,Huang Junming,Li Zhi,Xu Mingyou,Wu Kerong,Zhou Chenhe,Li Qidong,Zhu Chen,Liu Lianxin,Shang Xifu 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

The identification of key regulatory factors that control osteoclastogenesis is important. Accumulating evidence indicates that circular RNAs (circRNAs) are discrete functional entities. However, the complexities of circRNA expression as well as the extent of their regulatory functions during osteoclastogenesis have yet to be revealed. Here, based on circular RNA sequencing data, we identified a circular RNA, circFam190a, as a critical regulator of osteoclast differentiation and function. During osteoclastogenesis, circFam190a is significantly upregulated. In vitro, circFam190a enhanced osteoclast formation and function. In vivo, overexpression of circFam190a induced significant bone loss, while knockdown of circFam190a prevented pathological bone loss in an ovariectomized (OVX) mouse osteoporosis model. Mechanistically, our data suggest that circFam90a enhances the binding of AKT1 and HSP90β, promoting AKT1 stability. Altogether, our findings highlight the critical role of circFam190a as a positive regulator of osteoclastogenesis, and targeting circFam190a might be a promising therapeutic strategy for treating pathological bone loss.

Antecedents and consequence of the consumer's psychic distance in cross-border e-commerce

CHEN XI,김학민 경희대학교 글로벌 통상·금융연구원 2021 International Trade, Politics and Development Vol.5 No.2

The psychic distance often hinders the interaction between cross-border e-commerce (CBEC) and consumers. This paper aims to discuss the issues of psychic distance of consumers in the CBEC. In addition, it attempts to explain the factors that affect psychic distance from three dimensions of culture, economy and politics and the two different shopping behaviors caused by psychic distance.This research incorporates both theoretical and empirical studies. In this study, 249 validated questionnaires were selected from 300 Chinese CBEC consumers by snowball sampling, and the relationship between variables was tested using structural equation model (SEM). This was done through online research, and it is ensured that the data obtained are first-hand information.The paper suggests the theoretical model operationalizing CBEC psychic distance and the empirical analysis results show that all the six influencing factors have a positive impact on the psychic distance of consumers. Logistics infrastructure barriers in the economic dimension are confirmed as the major influencing factor, and the significance of the political dimension is relatively small. Based on consumers' uncertainty of various kinds of information, psychic distance subconsciously causes consumers to deviate in the cross-shopping process.Currently, research on e-commerce mainly focuses on saving trade costs and improving consumer welfare, while research on the internal impact of CBEC on consumers is insufficient. Psychic distance is a new concept in the field of cultural and social research. The originality of this paper is that the concept of psychic distance has been extended from overseas invested enterprises to research with CBEC consumers as the selected object. The obstacles of CBEC have been widely studied, but few are related to the closeness of consumers, or the inner feelings of consumers are ignored. In the context of CBEC, this paper lists the actual external factors and potential threats that may affect consumers' consumption concerns of CBEC from three dimensions. The real emotions of consumers in the face of these difficulties indirectly affect the purchase satisfaction and reduce the purchase desire. Consumer psychic distance is a real phenomenon in cross-border shopping, and it is almost inevitable for these difficulties. On the premise of inevitability, high psychic distance will slow down cross-border shopping in the eyes of consumers.

Buckling patterns of thin films on curved compliant substrates with applications to morphogenesis and three-dimensional micro-fabrication

Chen, Xi,Yin, Jie Royal Society of Chemistry 2010 SOFT MATTER Vol.6 No.22

<P>Self-assembled buckling patterns of thin films on compliant substrates have been subjected to extensive studies and shown great promise in micro-fabrication. However, most previous studies were limited to planar substrates, and the study of buckling of films on curved substrates has not received sufficient attention. With the constraining effect from various types of substrate curvature, numerous new types of buckling morphologies may emerge which not only enable true three-dimensional (3D) fabrication of microstructures and microdevices, but also have important implications for the morphogenesis of quite a few natural and biological systems. We review the scientific aspects of elastic buckling of thin films on several representative curved substrates, emphasizing the critical effect of substrate curvature, its interaction with other material/system parameters, ways to control the buckles based on mechanical and physical principles, and bridge them with prospective applications in biology, biomedical engineering, and small-scale fabrication.</P> <P>Graphic Abstract</P><P>Mechanical self-assembly, underpinned by the spontaneous buckling patterns of thin films on curved compliant substrates, is highly relevant to the morphogenesis of some biological systems and fabrication of 2D/3D microstructures. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0sm00401d'> </P>

Consumer Feedback Analysis Using LDA Approach in Cross-border E-commerce

CHEN XI,김학민 한국무역학회 2024 Journal of Korea trade Vol.28 No.2

Purpose - The objective of this research is to gain insight into consumer feedback regarding cross-border e-commerce, which is a pivotal avenue for companies venturing into global markets. It seeks to investigate the variety of themes present in consumer feedback in order to gain a more profound understanding of their preferences and concerns, ultimately influencing future market strategies. Design/Methodology – The present study utilizes an extensive collection of textual online evaluations and a text-mining LDA framework to analyze and classify potential themes in consumer feedback pertaining to cross-border e-commerce platforms. By quantifying the sentiment tendencies in consumer-related comments, sentiment analysis models that rely on emotion dictionaries as a foundation identify the polarity and intensity of emotions. Findings – The present study examined 1,500 consumer evaluations pertaining to Korean cosmetic products, sourced from a cross-border platform in Southeast Asia. The analysis unveiled five key subjects frequently referenced in consumer feedback. A subsequent sentiment analysis revealed that a significant proportion of consumer sentiments were positive. Nevertheless, consumers identified certain concerns in the minority of negative reviews, including packaging and delivery, product quality, and the absence of freebies. Originality/value - In a practical sense, this provides significant ramifications for the optimization of consumer experiences and the development of successful market strategies in the ever-changing global marketplace. This is especially advantageous for organizations striving for success in the fiercely competitive cross-border e-commerce industry. This study exceeds conventional survey methods in its methodology by offering more comprehensive and data-centric understandings of consumer attitudes and behaviors.

Frailty and Health-Related Quality of Life in Elderly Patients Undergoing Esophageal Cancer Surgery: A Longitudinal Study

Xi Chen,Rong Zheng,Xiuzhi Xu,Zhuzhu Wang,Guohong Huang,Rongrong Wu,Jingfang Hong 한국간호과학회 2024 Asian Nursing Research Vol.18 No.2

PurposeThis study aims to elucidate the longitudinal alterations in frailty and health-related quality of life experienced by elderly patients undergoing surgical treatment for esophageal cancer. Additionally, it seeks to ascertain the impact of preoperative frailty on postoperative health-related quality of life over time. Methods131 patients were included in the prospective study. Patients' frailty and health-related quality-of-life were assessed utilizing the Tilburg and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 at preoperative, 1 week, 1 month, and 3 months, postoperatively. Statistical analyses were performed using generalized estimating equations, repeated-measures analysis of variance, and linear mixed models (LMMs). ResultsOut of 131 patients, 28.2% had frailty before surgery, and the prevalence of frailty consistently higher after surgery compared with baseline (67.9%, 51.9%, and 39.7%). There was no significant change in frailty scores in preoperative frail patients within 3 months following surgery (p = .496, p < .999, p < .999); whereas in preoperative non-frail patients, the frailty scores increased at 1 week (p < .001) and then decreased at 1 month (p = .014), followed by no change at 3 months. In addition, preoperative frail patients had significantly worse global quality-of-life (β = −4.24 (−8.31; −.18), p = .041), physical functioning (β = −9.87 (−14.59; −5.16), p < .001), role functioning (β = −10.04 (−15.76; −4.33), p = .001), and social functioning (β = −8.58 (−15.49; −1.68), p = .015), compared with non-frail patients. ConclusionsA significant proportion of participants exhibited a high prevalence of preoperative frailty. These patients, who were preoperatively frail, exhibited a marked reduction in health-related quality-of-life, a more gradual recovery across various functional domains, and an increased symptom burden during the follow-up period. Therefore, it is crucial to meticulously identify and closely monitor patients with preoperative frailty for any changes in their postoperative physiology, role, and social functioning.