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排序方式: 共有105条查询结果,搜索用时 218 毫秒
11.
朱怀亮 《应用数学和力学(英文版)》2002,23(12):1413-1420
IntroductionRotatingshaftsarethemostvitalcomponentsofmodernindustrialandpowergenerationfacilities.DuetotheimportanceofthesecomponentstherewerewidelystudiesonthevibrationbehaviorofEuler_Bernoullirotatingshaftsusinganalyticalandnumericalmethods[1- 4 ].Howe… 相似文献
12.
In the Property and Casualty (P&C) ratemaking process, it is critical to understand the effect of policyholders’ risk profile to the number and amount of claims, the dependence among various business lines and the claim distributions. To include all the above features, it is essential to develop a regression model which is flexible and theoretically justified. Motivated by the issues above, we propose a class of logit-weighted reduced mixture of experts (LRMoE) models for multivariate claim frequencies or severities distributions. LRMoE is interpretable, as it has two components: Gating functions, which classify policyholders into various latent sub-classes; and Expert functions, which govern the distributional properties of the claims. Also, upon the development of denseness theory in regression setting, we can heuristically interpret the LRMoE as a “fully flexible” model to capture any distributional, dependence and regression structures subject to a denseness condition. Further, the mathematical tractability of the LRMoE is guaranteed since it satisfies various marginalization and moment properties. Finally, we discuss some special choices of expert functions that make the corresponding LRMoE “fully flexible”. In the subsequent paper (Fung et al., 2019b), we will focus on the estimation and application aspects of the LRMoE. 相似文献
13.
针对在线评价的发布时间、获得的“有用”的投票数以及是否被贴上“砖家”点评标签对在线评价信息可信度和消费者购买决策具有重要影响,提出一种基于在线评价信息且考虑评价信息可信度及消费者类型的酒店排序方法。首先,将不同类型消费者群体给出的在线评价信息转换成考虑在线评价信息可信度的区间中智数;其次,依据区间中智数距离测度公式确定针对目标群体的各消费者群体权重,进而依据INLNPA集成算子集结各消费者群体评价信息确定针对目标群体的酒店-属性决策矩阵;再次,依据区间中智集熵测度方法确定各属性权重,在此基础上,基于VIKOR方法得到针对目标群体的酒店排序结果;最后,通过一个实例分析说明该方法的有效性和可行性。 相似文献
14.
John F. Damrose Stephen N. Goldman Erik J. Groessl Lisa A. Orloff 《Journal of voice》2004,18(3):415-422
Injection of botulinum toxin (BT) into the muscles of the larynx is an effective treatment for the symptoms of spasmodic dysphonia (SD). To date, however, there have been no studies that have used blinded raters to assess the efficacy of BT injections on overall symptom severity in a cohort of SD patients followed over a prolonged period. In this study, 102 subjects with SD were treated with serial BT injections for up to 2 years. Voice recordings were obtained at several time points during treatment and were played to a panel of expert and novice listeners who rated them based on overall symptom severity in a single-blind fashion. Subjects demonstrated significant improvement over baseline at all time points. In addition, patients showed a sustained responsiveness to therapy over time. These results provide support for the efficacy of serial BT injections for SD and suggest that successful treatment may depend, in part, on patients' early recognition of returning symptoms. 相似文献
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Recursive equations for compound distribution with the severity distribution of the mixed type 总被引:1,自引:0,他引:1
YANG Jingping CHENG Shihong & WU Qin LMAM Department of Financial Mathematics Peking University Beijing China 《中国科学A辑(英文版)》2005,48(5):594-609
In this paper, recursive equations are obtained for compound distribution with the number of claims belonging to (a, b)-family and the severity distribution of the mixed type. Numerical methods to solve these equations are presented, and some numerical results are given. 相似文献
16.
Zhehao Huang Tianpei Jiang Zhenzhen Wang 《Mathematical Methods in the Applied Sciences》2020,43(12):7106-7134
In this paper, we explore a pricing model for corporate bond accompanied with multiple credit rating migration risk and stochastic interest rate. The bond price volatility strongly depends on potentially multiple credit rating migration and stochastic change of interest rate. A free boundary problem of partial differential equation is presented, which is the equivalent transformation of the pricing model. The existence, uniqueness, and regularity for the free boundary problem are established to guarantee the rationality of the pricing model. Due to the stochastic change of interest rate, the discontinuous coefficient in the free boundary problem depends explicitly on the time variable but is convergent as time tends to infinity. Accordingly, an auxiliary free boundary problem is constructed, whose coefficient is the convergent limit of the coefficient in the original free boundary problem. With some constraint on the risk discount rate satisfied, we prove that a unique traveling wave exists in the auxiliary free boundary problem. The inductive method is adopted to fit the multiplicity of credit rating. Then we show that the solution of the original free boundary problem converges to the traveling wave in the auxiliary free boundary problem. Returning to the pricing model with multiple credit rating migration and stochastic interest rate, we conclude that the bond price profile can be captured by a traveling wave pattern coupling with a guaranteed bond price with face value equal to one at the maturity. 相似文献
17.
水上交通事故严重程度影响因素的识别对从根本上减少严重事故件数、降低事故危害和损失具有重要意义。在历史事故报告的基础上,构建并量化事故影响因素集,提出以极限学习机(ELM)为一般事故、严重事故的二分类器,以遗传算法(GA)为因素搜索算法的GA-ELM因素识别模型。对发生在我国水域的737件水上交通事故进行实证研究,并与以支持向量机(SVM)为分类器的GA-SVM模型进行对比分析。结果表明,GA-ELM模型识别出时段、人为致因、环境致因等9个事故严重程度影响因素,较GA-SVM模型结果更为精简,且分类精度较不做因素识别时分别提高8.2%、7.1%。此外,GA-ELM大大缩短运算时间。由此可见,GA-ELM可为水上交通事故严重程度影响因素识别提供一个较好的方法。 相似文献
18.
Tasneem Gul Kazi Suraya Samejo Hassan Imran Afridi Asma Akhtar Jameel Ahmed Baig 《应用有机金属化学》2020,34(1):e5263
In the present study the cadmium (Cd) was determined in serum samples of psoriatic patients. The severity of psoriasis was evaluated according to criteria based on standard clinical diagnosis using Psoriasis Area Severity Index (PASI) score. In present study, an innovative tunable green solvent system based microextraction (TSS-ME) was applied for the enrichment of Cd in acid digested serum samples prior to determination with flame atomic absorption spectrometry. The hydrophobic complex of Cd-ammonium pyrrolidine thiocarbamate was extracted in a tunable solvent system which was prepared from a polybasic amine (N, N, N′, N′-tetramethyl-1, 4-diaminobutane), decanol and water system. The tunable green solvent system (TSS) which has zero ionic strength was converted to homogeneous monophasic polar hydrophilic phase via exposure to CO2 at different pressure and time duration. Then hydrophobic enriched Cd- ammonium pyrrolidine thiocarbamate was back extracted, using HNO3 (0.1 to 0.5 mol L−1) then the second round of TSS-ME was applied. The acidic aqueous phase enrich with analyte was separated from tunable solvent. The separated TSS was easily reused for up to 10 time for preconcentration purposes without loss of its enrichment character. The smoker and nonsmoker psoriatic patients at PASI >10, have two to three folds higher Cd levels in serum samples than healthy persons. 相似文献
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