Registration of the Seated Condylar Position (SCP/CR): Part I: Rationale

The purpose of this paper is to present the rationale for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles.

Registration of the Seated Condylar Position (SCP/CR): Part II: Technique: The Two-Piece Wax Bite Registration

The purpose of this paper is to present the technique for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles: a two-piece wax bite registration with deprogramming and no mandibular manipulation.

Optimization of Biodynamic Seated Human Models Using Genetic Algorithms

Many biodynamic models have been derived using trial and error curve-fitting technique, such that the error between the computed and measured biodynamic response functions is minimum. This study developed a biomechanical model of the human body in a sitting posture without backrest for evaluating the vibration transmissibility and dynamic response to vertical vibration direction. In describing the human body motion, a three biomechanical models are discussed (two models are 4-DOF and one model 7-DOF). Optimization software based on stochastic techniques search methods, Genetic Algorithms (GAs), is employed to determine the human model parameters imposing some limit constraints on the model parameters. In addition, an objective function is formulated comprising the sum of errors between the computed and actual values (experimental data). The studied functions are the driving-point mechanical impedance, apparent mass and seat- to-head transmissibility functions. The optimization process increased the average goodness of fit and the results of studied functions became much closer to the target values (Experimental data). From the optimized model, the resonant frequencies of the driver parts computed on the basis of biodynamic response functions are found to be within close bounds to that expected for the human body.

Deep- Seated Tectonic Activation of Tancheng-Lujiang Fault Zone and Its Control over Jiaodong Gold Concentrated Region, China

A comprehensive discussion on the deep seated genesis of gold metallogenic materials and the tectono magmatic controls over gold deposits is given in this paper, which is based on the crustal and upper mantle structural characteristics of the Jiaodong massif, the property, activation history and styles of the Tancheng Lujiang fault zone, as well as a series of accompanying tectono magmatic events. Prediction for further prospecting gold deposits in the area is also made.

The Effect of Seated Baduanjin Exercise on Psychological State, Fatigue Symptoms, and Quality of Life in Maintenance Hemodialysis Patients

Objective:To evaluate the intervention effects of seated Baduanjin exercise on patients undergoing maintenance hemodialysis(MHD).Methods:A total of 108 MHD patients admitted between July 2022 and July 2023 were selected.They were randomly assigned into two groups:the experimental group,with 55 patients,who received seated Baduanjin exercise combined with leg exercises during dialysis;and the control group,with 53 patients,who only performed leg exercises during dialysis.The psychological state,fatigue symptoms,quality of life,and sleep quality scores were compared between the two groups,and exercise endurance was recorded.Results:After the intervention,the psychological state scores in the experimental group were lower than those in the control group,the fatigue symptom scores were lower,the quality of life scores were higher,the sleep quality scores were lower,and the exercise endurance was higher(P<0.05).Conclusion:Seated Baduanjin exercise can improve the negative psychological state and fatigue symptoms of MHD patients,enhance their quality of life and sleep quality,and effectively increase their exercise endurance.

Vertical vibration characteristics of seated human bodies and a biodynamic model with two degrees of freedom

Understanding the vibration characteristics of a seated human body is critical for evaluation and improvement of ride comfort of various passenger vehicles. There have been very little publications about the vibration characteristics of a seated Chinese human body. By using wide-band white noise excitations and a homemade seat sensor, vertical vibration tests were carried out on 28 volunteers. Apparent masses were obtained for each volunteer at a frequency range of 1-20 Hz for various excitation le-vels. A biodynamic model, which has two degrees of freedom in parallel and includes a frame mass, was chosen to describe the vertical vibration characteristics of the seated human body. The model parameters were identified by means of a Gauss-Newton method with an error function defined in terms of both real and imaginary parts of the apparent mass against frequency. Based on the averaged data of the mass-normalized apparent mass from experiments, the model parameters and corresponding modal parameters were obtained for seated Chinese people at ages of 20-25 with standard weight. The apparent masses predicted by the biodynamic model with identified parameters agree very well with those obtained from experiments. Statistical analysis demonstrates the influence of volunteer’s height and weight on the model parameters for a seated human body.

A human-sensitive frequency band vibration isolator for heavy-duty truck seats

In this study,a human-sensitive frequency band vibration isolator(HFBVI)with quasi-zero stiffness(QZS)characteristics for heavy-duty truck seats is designed to improve the comfort of heavy-duty truck drivers on uneven roads.First,the analytical expressions for the force and displacement of the HFBVI are derived with the Lagrange equation and d'Alembert's principle,and are validated through the prototype restoring force testing.Second,the harmonic balance method(HBM)is used to obtain the dynamic responses under harmonic excitation,and further the influence of pre-stretching on the dynamic characteristics and transmissibility is discussed.Finally,the experimental prototype of the HFBVI is fabricated,and vibration experiments are conducted under harmonic excitation to verify the vibration isolation performance(VIP)of the proposed vibration isolator.The experimental results indicate that the HFBVI can effectively suppress the frequency band(4-8 Hz)to which the human body is sensitive to vertical vibration.In addition,under real random road spectrum excitation,the HFBVI can achieve low-frequency vibration isolation close to 2 Hz,providing new prospects for ensuring the health of heavy-duty truck drivers.

Design of Fully Automatic Specification Selection System for Resistance Welding Equipment

A system for fully automatic selection of welding specifications in resistance welding equipment has been developed to address the problem of workers frequently choosing the wrong specifications during manual welding of multiple parts on a single machine in automobile factories. The system incorporates an automatic recognition system for different workpiece materials using the added machine fixture,visual detection system for nuts and bolts,and secondary graphical confirmation to ensure the correctness of specification calling. This system achieves reliable,fully automatic selection of welding specifications in resistance welding equipment and has shown significant effects in improving welding quality for massproduced workpieces,while solving the problem of specification calling errors that can occur with traditional methods involving process charts and code adjustments. This system is particularly suitable for promoting applications in manual welding of multiple parts on a single machine in automobile factories,ensuring correct specification calling and welding quality.

Investigation and Application on the Vertical Vibration Models of the Seated Human Body

Investigation of the vertical vibration characteristics of the seated human body is beneficial for the design and development of vehicle ride comfort.In this study,we first established models of the seated human body with two,three and four degrees of freedom(DOF).Then,the vibration characteristics of 30 volunteers were tested under standard conditions with a vibration test rig to obtain data for the apparent mass,driving point mechanical impedance,and seat-to-head transfer function.Based on the experimental data,the parameters of these models are identified and the results show that the four-DOF model can simulate the vertical vibration characteristics of the seated human body more comprehensively.Then,different seated human body models were applied to optimize the damping of shock absorber.The results show that the optimized damping with the four-DOF Chinese seated human body model is 27%more than that with rigid mass and 7%less than that with ISO 5982:2001 seated human body model.

Design and Implementation of Library Seating Management System

The library seating management system is an important part of the library’s modern services. The system is based on the Spring and Spring Boot framework, and the system realizes a series of functions such as real-time query, reservation, and cancellation of seat resources, providing users with great convenience. With a simple operation, users can know the availability of seats in the library in real time and reserve them according to their needs. At the same time, the system also provides rich management functions, enabling administrators to easily configure and manage seat resources. The addition, deletion, modification and review of users, the generation of seats, the viewing of user usage records, and the addition or deletion of points for users’ usage can also be carried out. This not only improves the management efficiency, but also provides more scientific and accurate data support for the management of the library. The system not only optimizes the user experience, but also promotes the scientific management and efficient utilization of library resources, and provides strong support for the modern services of the library.

Effects of backrest density on lumbar load and comfort during seated work

Background Seated workplaces have greatly increased in China. Many researchers have found that seated work is a risk factor in the development of low-back pain. Backrest can reduce the load on the lower back by transmitting more of the weight from the upper body to the floor via the backrest so as to prevent low-back pain. To design a suitable chair backrest for seated office work, some backrest parameters must be optimized. In this study, the role of backrest density on lumbar load and comfort were investigated. The goal of the study was to help establish criteria with which backrests that alleviate and prevent low back pain during seated office work can be designed and selected. Methods Twenty volunteers （10 men and 10 women） were seated in three backrest conditions （10 kg/m^3, 25 kg/m^3, and 40 kg/m^3）. Pressure data, including contact pressure （CP）, peak contact pressure （PCP） and contact area were collected during 15-minute trial. Subjective data were collected after each pressure test. Results Backrest density had a significant effect on backrest pressure variables. CP and PCP increased with increasing backrest density. Contact area decreased with increased density. In terms of user preference, the backrest with low density was most highly rated. Conclusions Backrest density plays an important role in lumbar load and comfort during seated work. During designing and selecting backrests, backrest density should be focused on so as to alleviate and prevent low-back pain during seated office work. Backrest density at 10 kg/m^3 got the lowest CP and PCP and largest contact area. Backrest with low density can reduce lumbar pressure and increase support contact area, which could raise comfort feeling. Backrest density at 10 kg/m^3 is better to maintain a balance between providing effective support and alleviating excess lordosis.

Numerical study on erosion behavior of sliding sleeve ball seat for hydraulic fracturing based on experimental data

The sleeve sealing ball seat is one of the important components in the multistage fracturing process of horizontal wells.The erosion and wear of the surface will decrease the sealing performance of the fracturing ball and the ball seat.This leads to pressure leakage during the fracturing process and fracturing failure.In this paper,combined with the actual ball seat materials and working conditions during the fracturing process,the erosion tests of ductile iron and tungsten carbide materials under different erosion speeds,angles,and mortar concentrations are carried out.Then the erosion test results were analyzed by mathematical fitting,and a set of erosion models suitable for sliding sleeve setting ball seat materials were innovatively established.For the first time,this paper combines the erosion model obtained from the experiment and the computational fluid dynamics(CFD)with Fluent software to simulate the erosion of the ball seat.Based on the simulation results,the morphology of the sliding sleeve seat ball after erosion is predicted.Through analysis of the test and simulation results,it is showed that the erosion rate of tungsten carbide material is lower and the wear resistance is better under the condition of small angle erosion.This research can offer a strong basis for fracturing site selection,surface treatment methods,and prediction of failure time of ball seats.

Real-Time CNN-Based Driver Distraction&Drowsiness Detection System

Nowadays days,the chief grounds of automobile accidents are driver fatigue and distractions.With the development of computer vision technology,a cutting-edge system has the potential to spot driver distractions or sleepiness and alert them,reducing accidents.This paper presents a novel approach to detecting driver tiredness based on eye and mouth movements and object identification that causes a distraction while operating a motor vehicle.Employing the facial landmarks that the camera picks up and sends to classify using a Convolutional Neural Network(CNN)any changes by focusing on the eyes and mouth zone,precision is achieved.One of the tasks that must be performed in the transit system is seat belt detection to lessen accidents caused by sudden stops or high-speed collisions with other cars.A method is put forth to use convolution neural networks to determine whether the motorist is wearing a seat belt when a driver is sleepy,preoccupied,or not wearing their seat belt,this system alerts them with an alarm,and if they don’t wake up by a predetermined time of 3 s threshold,an automatic message is sent to law enforcement agencies.The suggested CNN-based model exhibits greater accuracy with 97%.It can be utilized to develop a system that detects driver attention or sleeps in real-time.

Adaptive Seat Cover for Motorsports and Daily Driving Situations

Automotive seat design presents an ongoing challenge as it involves balancing conflicting customer requirements, ranging from comfort and support to adaptability for diverse body types and custom-molded fit. Original equipment manufacturers often struggle to address the diverse needs dictated by the environment of use in automotive seat design. In response to these deficiencies, this paper employs the design thinking approach/model to explore the gaps in automotive seats comprehensively. The study provides valuable recommendations and documents the exploratory work carried out to bridge these gaps and enhance the overall automotive seat design. By utilizing design thinking principles, this research aims to pave the way for innovative solutions that meet the evolving demands of drivers, ensuring a more comfortable and safer driving experience for daily driving, and better performance for motorsports. Additionally, we present a comprehensive three-phase rapid prototyping approach to develop and showcase the functions of race car modifications, aiming to demonstrate their efficacy and gather valuable feedback from potential customers. By recognizing the significance of nurturing beginners’ interest and skill development, the motorsports community can encourage wider participation and ensure a vibrant future for the sport. .

“营改增”的影响效应研究——以上海市的改革试点为例

本文选取上海市的交通运输业、通讯业和建筑业与地方财政收入相关的24个序列,利用TRAMO/SEATS方法对"营改增"结构性减税政策效应进行实证检验。结果表明,"营改增"对交通运输业发展的促进作用在短期来看有限,"营改增"对通讯业和建筑业的改革红利预期较低,说明本轮较窄范围内的试点改革对产业发展的影响效应还未充分显现。最后,以分析结论为基础,就今后"营改增"的实施路径提出相关的政策建议。

居民消费价格指数季节调整实证研究

文章首先对居民消费价格指数季节调整的原因、季节调整方法的发展过程和应用进行了说明,着重介绍了国际上最新流行的X-12-ARIMA和TRAMO/SEATS季节调整方法,然后用X-12-ARIMA方法对上海市居民消费价格指数序列进行季节调整、分析和预测,并结合使用TRAMO/SEATS方法解决中国与国外明显不同的春节假日因素的调整问题,最后提出我国季节调整面临的问题。

季节调整方法综述及比较

Seasonal adjustment has been widely used in statistic analyses.Nowadays,the research on seasonal adjustment methods mainly concentrates on X-11,X-12 etc in China,lacking the whole understanding of foreign seasonal adjustment methods,and the latest progress of seasonal adjustment methods has been less introduced.In this article,various seasonal adjustment methods were introduced,and a comparison of their characteristics and applications was made.It is helpful that statistical organizations can develop appropriate seasonal adjustment methods,concerning different kinds of data.

盐城麋鹿生态旅游区游客变化特征及预测

生态旅游区的发展受到诸多确定性因素和随机性因素的共同作用,并反映于旅游区游客观测序列。通过构建游客序列分析框架,提出了游客序列分析的理论模型。并以江苏盐城麋鹿生态旅游区为例,集成多种数学方法,进行了游客序列的分解、调整和综合预测的实证分析。运用Tramo/Seats方法进行季节调整分析可有效提取时间序列各组分,从而获得了不同尺度的作用模式,所获得的去噪序列为预测研究提供了基础资料。基于ARIMA模型、Winter加法模型、Winter乘法模型和Tramo/Seats模型的综合预测表明,麋鹿生态旅游区未来两年年平均新增游客数量在1.95-3.14万人次之间。各方法预测结果间的差异与其建模思路及实现方法有关,因此集成多种方法进行预测,并进行对比分析,有助于获得对游客波动变化更为全面的认识,同时所提供的多种可能预测方案,可为生态旅游区容量控制、旅游环境资源的保护与开发及旅游区的管理决策提供参考依据。

居民消费价格指数的季节调整及短期预测

文章首先论述了季节调整方法的发展过程;然后把居民消费价格指数的同比数据转换为定基比数据,运用国际上最新流行的X-12-ARIMA程序对我国居民消费价格指数时间序列进行季节调整;再运用TRAMO/SEATS方法剔除中国特有的春节假日因素;最后对CPI进行短期预测,得出了我国的通货膨胀可能还会持续一段时间的结论。

基于ARIMA模型的春节因素调整方法研究

目的研究基于ARIMA模型的春节因素调整方法。方法构建通用的春节因素变量,将其作为回归变量纳入季节性ARIMA回归模型(regARIMA或TRAMO),采用AIC或BIC对模型的效果进行判断,确定最优模型。采用广义最小二乘法或最大似然法进行参数估计,并根据估计出的回归系数计算春节因素的影响程度。通过实例分析对上述方法进行实证。结果实例分析表明,引入春节因素变量后的季节调整方法能有效地消除春节因素对时间序列的影响,并能定量分析春节因素的影响程度。结论构建的春节因素变量具有较好的适用性,基于ARIMA模型的春节因素调整方法能有效地运用于时间序列的季节调整,为分析春节因素的影响提供了一种新的方法。