Substitutive Press-Bolster and Press-Ram Models for the Virtual Estimation of Stamping-Tool Cambering

Today’s stamping simulations are realized by ignoring the elastic deformation of the press and tooling system through the assumption of a rigid behavior and a perfect press stroke. However, in reality, the press and tool components deform elastically and are one of the major error sources for the final adjustment and blue-spotting of the dies. In order to tackle this issue, a new approach is proposed in this study that substitutes the press stiffness by means of a substitutive model composed of cost-effective shell and beam elements. The substitute model was calibrated using full-scale measurements, in which a 20,000 kN trial press was experimentally characterized by measuring its deformation under static loads. To examine the robustness of the substitute model, a medium-size tool and a large-size tool were simulated together with the substitutive model. To this end, a B-pillar tool was re-machined based on the substitute-model results and a new cambering procedure was proposed and validated throughout the blue-painting procedure. The newly developed substitute model was able to replicate the global stiffness of the press with a high accuracy and affordable calculation time. The implementation of the findings can aid toolmakers in eliminating most of the reworking and home-line trials.

Moving Toward Individual-Specific Automotive Seat Design: How Individual Characteristics and Time Alter the Selected Lumbar Support Prominence

Objective To explore how individual characteristics influence selected lumbar support prominence (LSP), seated lumbar flexion, seatback average pressure, contact area, and center of pressure (CoP) location before and after 1 hr of driving. Background An LSP can alter posture and may reduce low back pain during prolonged driving. Although LSP preference varies across individuals and may change over time, few investigations have explored the time-varying response to individually selected adjustable seat parameters. Method Forty individuals selected LSP settings in an automotive seat through a series of systematic adjustment trials. The average LSP setting was fixed for a 1-hr driving simulation, followed by one final adjustment trial. Regressions were performed between individual characteristics and selected LSP, lumbar posture, and measures of seatback pressure from the initial adjustment trials. ANOVAs were performed to determine the effect of time and sex on these dependent variables. Discomfort was also monitored throughout the protocol. Results Individual’s standing lumbar lordosis, selected LSP, and height and mass were significant predictors for seated lumbar flexion, seatback average pressure, and contact area, respectively. Discomfort levels remained low; however, following the driving protocol, individuals altered their posture to decrease lumbar flexion and increase seatback average pressure without significant adjustments to the LSP. Conclusion These findings highlight individual characteristics to consider in automotive seat design and that the method for determining LSP settings may facilitate appropriate LSP selection. Application A systematic method to determine LSP settings may reduce discomfort and automate seat adjustments, such that only short-term postural adjustments may be required.

Development of a Performance-Related Framework for Asphalt Mixture Design for the Illinois Tollway

Various agencies have begun to research and introduce performance-related specifications (PRS) for the design of modern asphalt paving mixtures. The focus of most recent studies has been directed toward simplified cracking test development and evaluation. In some cases, development and validation of PRS has been performed, building on these new tests, often by comparison of test values to accelerated pavement test studies and/or to limited field data. This study describes the findings of a comprehensive research project conducted at Illinois Tollway, leading to a PRS for the design of mainline and shoulder asphalt mixtures. A novel approach was developed, involving the systematic establishment of specification requirements based on: 1) selection of baseline values based on minimally acceptable field performance thresholds; 2) elevation of thresholds to account for differences between short-term lab aging and expected long-term field aging; 3) further elevation of thresholds to account for variability in lab testing, plus variability in the testing of field cores; and 4) final adjustment and rounding of thresholds based on a consensus process. After a thorough evaluation of different candidate cracking tests in the course of the project, the Disk-shaped Compact Tension—DC(T)—test was chosen to be retained in the Illinois Tollway PRS and to be presented in this study for the design of crack-resistant mixtures. The DC(T) test was selected because of its high degree of correlation with field results and its excellent repeatability. Tailored Hamburg rut depth and stripping inflection point thresholds were also established for mainline and shoulder mixes.

Research on Dynamic Storage Location Assignment of Picker-to-Parts Picking Systems under Traversing Routing Method

Considering time-varying demand of online retail industry, the traditional static storage location assignment is converted into a multistage storage location assignment process based on the idea of gradual and small-step-forward optimization, which can respond to rapid changes in demand by adjusting the storage location of SKUs in the warehouse in real time and dynamically. First, the study formulates the framework dynamic storage location assignment. Then, the adjustment gain model of dynamic storage location assignment is built, and a genetic algorithm is designed to find the final adjustment solution. Finally, the computer program is developed to simulate the whole process. Simulation and data analysis results show that dynamic storage location assignment can effectively improve picking efficiency when the average order size is small and large demand correlation strength. Dynamic storage location assignment simplifies the warehouse operation process by combining the picking operation and storage location assignment into one without changing the picker’s current walking route, which can offer some theoretical guidance for online retail enterprises implementing dynamic storage location assignment.

Experimental testing of heat flux sensors based on the inverse problem technique

In final adjustment of thermally-loaded elements of space structures information on thermal loads (heat fluxes and surface temperatures) for the whole period of flight in the atmosphere is of primary importance. The level of temperature and the processes taking place on the surface of the heat shield do not always allow using conventional methods of measuring thermal loads. In this case determining thermal loads by the results of measuring the temperature at several points of elements of the heat shield structure is an alternative to direct measurements. The aim of this work is to develop and test sensors for measuring heat loading of thermal-protective coating of modern descent vehicles, as well as to test the developed methods of carrying out thermo-physical tests. Heat flux sensors for indestructible composite fibrous materials with a high degree of non-uniformity are described in the paper.

Statistical diagnostics of measurements

The algorithm of statistical diagnostics used for the detection of measurement faults critical for ACS of manufacturing equipment and power units has been considered. Noise interference and pulse jamming and also a shift, drift and sensitivity loss of a measuring channel belong to them. A preliminary synthesis of an algorithm was carried out in the structure of a self-contained complex having a simulator of measurement faults, and their final adjustment is carried out according to the results of semi-natural tests. The latter provides for the application of diagnostic algorithms to processing records of natural information.

Saturation Point of Superplasticizers Determined by Rheological Tests for Self Compacting Concrete

The dosage of superplasticizer is first determined in mortar mixtures and it is after adjusted in concrete mix trials. Other self compacting concrete (SCC) mix proportioning methods rely on the definition of the superplasticizer saturation dosage in pastes. These approaches to mix design have advantages over the ones based exclusively on concrete batching because it is less expensive and material demanding to perform tests in mortar and paste than in concrete. This paper presents the results of an experimental research carried out to investigate the use of tests performed in paste to define the optimum dosage of superplasticizer for self-compacting concrete. The materials employed were Portland cement, pozzolana and three types of superplasticizers: poly naphthalene sulfonate (PNS), poly melamine sulfonate (PMS) and a polycarboxylate. The saturation point of each superplasticizer was determined in pastes by rheological tests using a coaxial cylinder rheometer AR2000. Self-compacting concretes were prepared using the superplasticizer contents found. The results obtained led to the conclusion that in SCC mixture proportioning methods, the determination of the superplasticizer content in the paste phase is paramount. Nevertheless, final adjustment of w/c+f ratio was always needed in order to produce SCC.

Job satisfaction of Chilean workers. A model of structural equations

Job satisfaction as a psychosocial phenomenon is associated with a set of attitudes that have an important role in the accomplishment of objectives by organizations in general. In addition, the modernization of managerial practices and the professionalization of both public management and administration, implies the necessity of knowing the attitudes related to work that have a greater influence on workers' job satisfaction. This research seeks to characterize the employees of Chilean public institutions regarding their job satisfaction and six different attitudes that make up this construct. The sample comprised 216 Chilean employees, who answered a survey which had six scales and a reliability coefficient of about 0.8, which defines a valid internal consistency scale. By applying models of structural equations, through a confirmatory factorial analysis, the relationship between the different dimensions that explain the the workers' job satisfaction is studied. Finally, the results reveal that the model of first level structural equations, after a final adjustment, selects four of the six original dimensions, which are: job satisfaction as a whole, satisfaction with the way the work is done, satisfaction with development opportunities and satisfaction with the relationship between the employer and the employee. These dimensions produce positive effects on the overall job satisfaction construct, being “satisfaction with the relationship between the employer and the employee” the best one, as reflected by its indicators, which for this sample correspond to the employer's supervision satisfaction and the proximity and frequency with which they are supervised.

Estimation of the interpolation error of a three-step rotation algorithm using recorded images with rotated test pattern as ground truth

Nowadays, the surgical microscope is the goldstandard for microsurgical procedures. Additional functionalities such as surgical navigation, data injection or imageoverlay are providing additional valuable information to the surgeon. For substituting the conventional optical system by a fully-digital multi-camera setup the three dimensional (3D) reconstruction of the scenery in the field of view is required. However, for in camera-based systems, an exact alignment of the cameras is a challenging task. Therefore, a final adjustment through a digital image rotation becomes necessary. Even though the digital rotation is a commonly used procedure, it leads to unavoidable errors because of the discretized grid of the image. Previous research reported in literature has demonstrated that the method of digitally rotating the images combined with the Fourier interpolation delivers the results of best quality. Nevertheless, the performance evaluation of this algorithm was carried out rotating an image in multiple threestep rotations to a total of 90 or 180 degrees and comparing it to the original image rotated in one step. This is a valid approach because a rotation of 90 or 180 degrees does not produce rotation artifacts. In this research project, we verify the performance of the three-step rotation algorithm using recorded images for which the test pattern was rotated as ground truth. A series of photographs with a rotation angle of 3 to 45 degrees was created. The advantage of this setup is that the result of the digital rotation can be directly compared to the recorded image. In addition, with the knowledge obtained about the interpolation error, we can improve pixel matching in the further triangulation used for 3D reconstruction. By doing so, the estimation of the interpolation error helps to reduce the triangulation error.

An Acquisition and Display Method for Multi-View 3D Models

Based on the technology of OpenGL and DirectX Wrapper, this paper designs and implements a new general method of data collection and display for the existing three-dimensional models using in multi-view 3D display system. Firstly, by using the technology of OpenGL/DirectX Wrapper, it obtains the application information such as the models, calls and associated data. Secondly, it sends the information to all rendering nodes. Then, according to the multi-view system projection array number and expected angle threshold parameter, each rendering node does the final adjustment and calibration on the obtained information sequentially for multi-view image rendering. Finally, each node transmits corresponding viewpoint image rendered by themselves to the projection equipment, and displays stereo images through 3D device synchronously. This method can be applied to all application programs based on OpenGL or DirectX Library. It is a general method for collecting and displaying multi-view 3D data sources. Experimental results show that this method is of high acquisition and rendering process, the image quality is the same as the source and stereoscopic displays strong. It has a wide range of applications and research value in the field of Engineering.