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Used car price prediction based on XGBoost and retention rate

The Journal of China Universities of Posts and Telecommunications 2024年第3期31卷 72-79页

作者： Shen Yutian Chen Jian Dai Min Zhang Sirui Xu Jing Wang Qing College of Mechanical Engineering Yangzhou UniversityYangzhou 225127China College of Economics and Management Southeast University Chengxian CollegeNanjing 210088China Shandong Shuncheng Automobile Trade Co. LtdJinan 250000China

In order to improve the accuracy of used car price prediction,a machine learning prediction model based on the retention rate is proposed in this ***,a random forest algorithm is used to filter the variables in the *** main characteristic variables that affect used car prices,such as new car price,service time,mileage and so on,are filtered ***,the linear regression classification method is introduced to classify the test data into high and low retention rate *** that,the extreme gradient boosting(XGBoost)regression model is built for the two datasets *** prediction results show that the comprehensive evaluation index of the proposed model is 0.548,which is significantly improved compared to 0.488 of the original XGBoost ***,compared with other representative machine learning algorithms,this model shows certain advantages in terms of mean absolute percentage error(MAPE),5%accuracy rate and comprehensive evaluation *** a result,the retention rate-based machine learning model established in this paper has significant advantages in terms of the accuracy of used car price prediction.

关键词： random forest data dimensionality reduction extreme gradient boosting(XGBoost) retention rate price prediction

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Optimizing feeding regimen of replacement gilts to improve their reproductive performance and retention rate of their first 2 parities

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Animal Nutrition 2023年第1期12卷 227-235页

作者： Jiajian Tan Miaomiao Wang Haiqing Sun Chao Wang Hongkui Wei Siwen Jiang Yuanfei Zhou Jian Peng Department of Animal Nutrition and Feed Science College of Animal Science and TechnologyHuazhong Agricultural UniversityWuhan 430070China Key Lab of Agricultural Animal Genetics Breeding and Reproduction of Ministry of Education&Key Lab of Swine Genetics and Breeding of Ministry of AgricultureHuazhong Agricultural UniversityWuhan 430070China The Cooperative Innovation Center for Sustainable Pig Production Wuhan 430070China Guangxi Yang Xiang Joint Stock Company Guigang 537000China

The effects of age,body weight(BW),and backfat thickness(BF)of replacement gilts at first estrus and first mating on their subsequent reproductive performance and retention of their first 2 parities as sows was evaluated.A total of 3,025 Danish replacement gilts were categorized by farm(allocated to 4 farms),cross combination,age,BW and BF at first estrus and first mating,estrous cycle number at first mating,and flush feeding before first *** result shows that all the factors mentioned above were significantly associated with reproductive performance and retention rates of the first 2 *** 3 had more piglets born alive per litter(BA)(Pretention rate of the 2 parities than Landrace×Yorkshire(L×Y)replacement gilts(Pretention rate of the 2 parities than no flush feeding(P<0.05).Because the effects of replacement gilts rearing parameters on reproductive performance traits differed,we used 100 replacement gilts as a unit and the total number of weaned piglets from the first 2 parities as a new *** gilts undergoing their first estrus between 180 and 210 d of age at 115 to 124.9 kg BW and 14 to 15 mm BF had significantly higher reproductive indexes for their first 2 parities per 100 replacement *** gilts that mated between 210 and 230 d of age at 140 to 149.9 kg BW and 15 to 16 mm BF had optimal reproductive *** results provide a new insight into the complex relationships among these reproductive performance traits and may help guide successful management of replacement gilts as a pivotal starting point for future fertility and longevity of rearing herds.

关键词： Replacement gilts Rearing parameter Reproductive performance retention rate

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Long-term Effectiveness of Antiepileptic Drug Monotherapy in Partial Epileptic Patients： A 7-year Study in an Epilepsy Center in China

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Chinese Medical Journal 2015年第22期128卷 3015-3022页

作者： Fei Zhu Sen-Yang Lang Xiang-Qing Wang Xiao-Bing Shi Yun-Feng Ma Xu Zhang Ya-Nan Chen Jia-Tang Zhang Department of Neurology Chinese People's Liberation Army General Hospital Beijing 100853 China Department of Neurology China National Clinical Research Center for Neurological Diseases Beijing Tiantan Hospital Capital Medical University Beijing 100050 China

Background： It is important to choose an appropriate antiepileptic drug （AED） to manage partial epilepsy. Traditional AEDs, such as carbamazepine （CBZ） and valproate （VPA）, have been proven to have good therapeutic effects. However, in recent years, a variety of new AEDs have increasingly been used as first-line treatments for partial epilepsy. As the studies regarding the effectiveness of new drugs and comparisons between new AEDs and traditional AEDs are few, it is determined that these are areas in need of further research. Accordingly, this study investigated the long-term effectiveness of six AEDs used as monotherapy in patients with partial epilepsy. Methods： This is a retrospective, long-term observational study. Patients with partial epilepsy who received monotherapy with one of six AEDs, namely, CBZ, VPA, topiramate （TPM）, oxcarbazepine （OXC）, lamotrigine （LTG）, or levetiracetam （LEV）, were identified and followed up from May 2007 to October 2014, and time to first seizure after treatment, 12-month remission rate, retention rate, reasons for treatment discontinuation, and adverse effects were evaluated. Results： A total of 789 patients were enrolled. The median time of follow-up was 56.95 months. CBZ exhibited the best time to first seizure, with a median time to first seizure of 36.06 months （95% confidential interval： 30.64~4.07）. CBZ exhibited the highest 12-month remission rate （85.55%）, which was significantly higher than those of TPM （69.38%, P = 0.006）, LTG （70.79%, P= 0.001）, LEV （72.54%, P = 0.005）, and VPA （73.33%, P = 0.002）. CBZ, OXC, and LEV had the best retention rate, followed by LTG, TPM, and VPA. Overall, adverse effects occurred in 45.87% of patients, and the most common adverse effects were memory problems （8.09%）, rashes （7.76%）, abnormal hepatic function （6.24%）, and drowsiness （6.24%）. Conclusion： This study demonstrated that CBZ, OXC, and LEV are relatively effective in managing tbcal epilepsy as measured by time to first seizure, 12-

关键词： 12-month Remission rate Antiepileptic Drug Partial Epilepsy retention rate

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Elaboration of Ceramic Pot Filter from Kaolinite (Cameroon Clay) for the Elimination of Suspended Particles from Domestic Drinking Water

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Journal of Modern Physics 2023年第8期14卷 43-60页

作者： Celestine Asobo Yanu Ngiongboung Nguiamba Joseph Marie Sieliechi Martin Benoit Ngassoum Faculty of Science Department of Chemistry University of Buea Buea Cameroon National School of Agro-Industrial Sciences Department of Applied Chemistry University of Ngaoundere Ngaoundere Cameroon

The objective of this work was to elaborate ceramic water filters from Kaolinite (Cameroon) clay for the elimination of suspended particles from domestic drinking water. In Sub-Sahara Africa and in Cameroon in particular health issues have been linked to the consummation of domestic tap water of high turbidity values both in the rural and urban areas. In order to remedy these problems, ceramic water pot filters have been elaborated in a pilot scale unit with aim of putting in place a unit production. The chemical composition, the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analyses of the raw materials (clay and rice husks) was determined. The crystal phases and scanning electron microscope of Wack clay was also determined. The ceramic pot filter membranes were fabricated from the formulations 70/20/10 of clay/porogen/chamotte respectively with the particle size of the raw material less than or equal to 500 μm. The formulated ceramic pot filters were then sintered at 900˚C in a furnace. These ceramic pot filters were characterized by determining their porosity, withdrawal percentages, water permeability, mechanical and chemical resistance. The study of the efficiency consisted in evaluating the retention rate and permeate flux with respect to time (days) with synthetic water suspensions of turbidity 100 NTU and particle size of 2 μm. The ceramic pot filters were made aiming at studying the efficiency after physical defouling of filters. Physical defouling consisted in brushing the inner surface of the ceramic pot filters with water and drying them at ambient temperature after being used for 11 days and reusing them under the same initial conditions. The produced ceramic pot filter had a volume of 4 L, an average porosity of 36.15%, shrinkage in mass or withdrawal percentage of 18.23%, a water permeability of 59.6 × 103 L∙h−2∙m−2, mechanical resistance of 6.8 MPa and corrosion resistance of

关键词： Ceramic Pot Filter retention rate Flux Defouling Formulation Production Cost

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Effects of operating conditions on membrane charge property and nanofiltration

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Frontiers of Chemical Science and Engineering 2011年第4期5卷 492-499页

作者： Li XU Li-Shun DU Jing HE School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Membrane Science and Desalination Technology Tianjin UniversityTianjin 300072China Lanpec Technologies Co. Ltd.Tianjin 300072China

The effects of the operating pressure,crossﬂow velocity,feed concentration,and temperature on the streaming and Zeta potential of the membranes were *** permeateﬂux and the retention rate under different nanoﬁltration operating conditions were also *** results show that the higher pressure,feed concentration,temperature,and lower crossﬂow velocity lead to the higher absolute value of streaming and Zeta *** permeateﬂux of the nanoﬁltration decreases with the feed concentration and increases with not only the pressure but also the crossﬂow velocity and *** higher the pressure and the crossﬂow velocity,the higher the retention *** lower feed concentration and higher temperature leads to lower retention *** effects of the operating conditions on the permeateﬂux and the retention rate were explained by the variation of the membrane charge property.

关键词： nanoﬁltration membrane streaming potential Zeta potential permeateﬂux retention rate

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Vacuum Application of Liquid Vitamin C to Extruded Fish Feed Pellets

Vacuum Application of Liquid Vitamin C to Extruded Fish Feed...

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国际农业工程大会

作者： Weiguo WangBioengineering Dept Henan University of Technology Zhengzhou 450052 China. Dept. of Animal Science and Technology Norway Agriculture University

＜正＞ In feed processing, the heat-labile additives such as vitamins, enzymes, flavors,probiotics and extracts from herbs can be easily deactivated by heat, pressure produced in conditioning, pelleting, extruding and drying. The post pelleting and extruding application can greatly reduce the loss of heat labile additives, decrease the cost of extra additive addition and improve animal

关键词： Vacuum application Vitamin C Extruded fish feed retention rate

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网络公司在产品研发中怎样通过收集反馈信息和提高透明度来保留和获得用户？

网络公司在产品研发中怎样通过收集反馈信息和提高透明度来保留和...

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作者： David Salczer 北京外国语大学

学位级别：硕士

Across this thesis I will try to show that there is a link between how companies succeed to acquire and retain customers through successful strategies of transparency and customers' *** idea is to show that companies that are transparent and close to their clients are more *** means that companies are more open,while feedbacks allow companies to collect metrics about customers,in order to build a product that fit the market *** drawing the emerging topic of transparency in the digital sector and the increasing use of new management and developing method thanks to *** will be explained what are two of the most important metrics in the digital sector:Acquisition and retention of customers/*** two metrics are the most important to show whether a digital company is on the right *** the methodology part through qualitative interviews which consists in questioning people who are confronted with these issues of acquisition and retention of users/customers in their digital product development,the objective is to understand how they perceive these relatively new notions of transparency and feedback collection and whether they apply them in their product *** shows that in every startup,transparency became an important topic which is related with costumer *** satisfaction is directly related to acquisition and retention *** the discussion of the findings we can say that the collecting of feedback and transparency are relatively linked together in most of digital *** helps companies to increase the confidence of users and costumers in to the *** are one of the best tool to be aware of what users/customers think about the product so that it is easier for companies to adapt their product in the right *** that fits the needs of users so that acquisition and retention of users are easier because users are getting more and more satisfied by

关键词： digital company acquisition rate retention rate company transparency

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何以留住乡村教师

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中小学学校管理 2019年第8期

作者：唐一鹏王恒

加强乡村学校的师资队伍建设成为我国现阶段义务教育的发展重点。基于G省特岗教师调研数据，采用量化与质性相结合的方式进行实证研究。教师留任的二元逻辑回归模型表明，年龄和地缘变量是影响特岗教师留任的关键因素。实地调研的结果... 详细信息

加强乡村学校的师资队伍建设成为我国现阶段义务教育的发展重点。基于G省特岗教师调研数据，采用量化与质性相结合的方式进行实证研究。教师留任的二元逻辑回归模型表明，年龄和地缘变量是影响特岗教师留任的关键因素。实地调研的结果则表明，“中央特岗计划”在有效引导地方财政配套的同时，变相加剧了地方财政负担；乡村教师不仅教学负担重，而且承担了过多教学之外的工作；物质条件匮乏、基础设施不健全仍然是阻碍乡村教师留任的重要原因。为了稳定乡村教师队伍，中央财政应该继续加大转移支付力度，解决地方财政的后顾之忧；同时，地方教育部门应该构建更为全面的乡村教师专业发展支持体系，并且在避免招聘中出现“本地化倾向”的同时，增强乡村教师的文化认同。

关键词：乡村教师特岗计划特岗教师留任率 rural teacher special-post plan special-post teacher retention rate

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透视国外远程教育降低辍学率的窗口

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成人教育学刊 2012年第5期

作者：刘永权牛健李莹

高辍学率是困扰中外远程教育健康发展的共性问题。2010年7月英国开放大学扩大参与中心(CWP，OUUK)出台了一份最新报告《22%——我们还能做得更好些吗？》，报告指出包括英国开放大学在内的世界上多所远程教育院校毕业率太低的现状，并... 详细信息

高辍学率是困扰中外远程教育健康发展的共性问题。2010年7月英国开放大学扩大参与中心(CWP，OUUK)出台了一份最新报告《22%——我们还能做得更好些吗？》，报告指出包括英国开放大学在内的世界上多所远程教育院校毕业率太低的现状，并用成本—效益分析法论证了高辍学率给学生、院校和社会造成的巨大危害，批驳了高辍学率是高质量的保证和在远程教育中无法避免的论点。报告还用较大篇幅说明了降低辍学率、提高保持率的一些有效措施，包括提供有利于学生保持率的支持服务、指导学生选择恰当的课程、设计有利于学生保持率的课程模块等。该报告给我国远程教育辍学问题研究者的启示是：在对我国远程教育辍学问题归因分析完成后，应该迅速转入对提高学生保持率的行动研究中去。

关键词：远程教育辍学研究保持率英国开放大学国际研究 distance education dropout research retention rate Open University of United Kingdom international research

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