Flexible scheduling of diagnostic tests in automotive manufacturing

The car of the future will be driven by software and offer a variety of customisation options. Enabling these customisation options forces modern automotive manufacturers to update their standardised scheduling concepts for testing and commissioning cars. A flexible scheduling concept means that every chosen customer configuration code must have its own testing procedure. This concept is essential to provide individual testing workflows where the time and resources are optimised for every car. Manual scheduling is complicated due to constraints on time, predecessor-successor relationships, mutual exclusion criteria, resources and status conditions on the car engineering and assembly line. Applied methods to handle the mathematical formulation for the corresponding industrial optimisation problem and its implementation are not yet available. This paper presents a procedure for automated and non-preemptive scheduling in the testing and commissioning of cars, which is built on a Boolean satisfiability problem on parallel and identical machines with temporal and resource constraints. The presented method is successfully implemented and evaluated on a variant assembly line of an automotive Original Equipment Manufacturer. This paper is the starting point for an automated workflow planning and scheduling process in automotive manufacturing.

An Entropy-Based Approach for Nonparametrically Testing Simple Probability Distribution Hypotheses

In this paper, we introduce a flexible and widely applicable nonparametric entropy-based testing procedure that can be used to assess the validity of simple hypotheses about a specific parametric population distribution. The testing methodology relies on the characteristic function of the population probability distribution being tested and is attractive in that, regardless of the null hypothesis being tested, it provides a unified framework for conducting such tests. The testing procedure is also computationally tractable and relatively straightforward to implement. In contrast to some alternative test statistics, the proposed entropy test is free from user-specified kernel and bandwidth choices, idiosyncratic and complex regularity conditions, and/or choices of evaluation grids. Several simulation exercises were performed to document the empirical performance of our proposed test, including a regression example that is illustrative of how, in some contexts, the approach can be applied to composite hypothesis-testing situations via data transformations. Overall, the testing procedure exhibits notable promise, exhibiting appreciable increasing power as sample size increases for a number of alternative distributions when contrasted with hypothesized null distributions. Possible general extensions of the approach to composite hypothesis-testing contexts, and directions for future work are also discussed.

High-efficient low-cost characterization of materials properties using domain-knowledge-guided self-supervised learning

Modern AI-assisted approaches have helped material scientists revolutionize their abilities to better understand the properties of materials. However, current machine learning (ML) models would perform awful for materials with a lengthy production window and a complex testing procedure because only a limited amount of data can be produced to feed the model. Here, we introduce self-supervised learning (SSL) to address the issue of lacking labeled data in material characterization. We propose a generalized SSL-based framework with domain knowledge and demonstrate its robustness to predict the properties of a candidate material with the fewest data. Our numerical results show that the performance of the proposed SSL model can match the commonly-used supervised learning (SL) model with only 5 % of data, and the SSL model is also proven with ease of implementation. Our study paves the way to expand further the usability of ML tools for a broader material science community.

Experimental Analysis and Multiscale Modeling of the Dynamics of a Fiber-Optic Coil

Fiber-optic gyroscopes (FOGs) are common rotation measurement devices in aerospace applications. They have a wide range of diversity in length and in the winding radius of the coil to meet system requirements. Every dimensional parameter in the coil influences the dynamic response of the system, eventually leading to measurement errors. In order to eliminate the errors and to qualify the system, after the design and production stages, a deep and comprehensive testing procedure follows. In this study, the dynamic behavior of a quadrupole wound fiber-optic coil is investigated. First, pre-wound fiber-optic coils are tested with an impact modal test, where the mode shapes and natural frequencies are determined with structural data acquisition. For the modal analysis, a finite element (FE) model is developed where a representative volume element (RVE) analysis is also included to properly consider the influence of the microstructure. The experimental and numerical results are compared and validated. Moreover, an estimation model is proposed for a type of coil with different fiber lengths. Finally, the estimated coil set is produced and tested employing the same methodology in order to illustrate the capacity of the developed framework.

A New Laboratory Technique to Enhance Proppant Consolidation During Propped Hydraulic Fracturing Treatment

The objectives of this investigation were to perform a rock mechanical study to evaluate long term stability of Resin-Coated Proppant (RCP), combined with various additives currently being used in screenless propped hydraulic fracturing completions in the sandstone formations. Thereby providing a tool for the industry to know exactly the duration of the shut-in time before putting a well back onto production. A new experimental method was developed to monitor the curing process of RCP as temperature increases. The velocity of both shear and compressional waves were being monitored as a function of temperature, while the tested RCP sample was being housed in a pressurized vessel. The pressurized vessel was subjected to a variable temperature profile to mimic the recovery of the reservoir temperature following a propped hydraulic fracturing treatment. The placed proppant should attain an optimum consolidation to minimize the potential for proppant flow back. The study has been performed on various types of RCP samples under a range of reservoir conditions. The role of closure stress, temperature, curing time and carrier fluids in attaining a maximum strength of RCP following a propped hydraulic fracturing treatment have been investigated. Also, the Unconfined Compressive Strength (UCS) of various types of RCP have been measured. The testing methods currently practiced in the industry to qualify proppant for field applications are based on physical characterization of several parameters such as the specific gravity of proppant, absolute volume, solubility, roundness, sphericity and bulk density. The sieve analysis, compressive strength, and API crush testing are also measured and reported. The API Recommended Practices; API RP56, API RP58 and API RP60 are the main procedures used to test the suitability of proppants for hydraulic fracturing treatment. However, there is no published API testing method for RCP; therefore this study introduces a new testing procedure, using acoustic velocity as a function of temperature and compressive strength as a function of time; to qualify a given RCP for a particular reservoir of known stress and temperature. The final outcome of this study is to establish a functional procedure for such measurements, in order to maximize the success of a propped hydraulic fracturing treatment and minimize the occurrence of flow back incidents.

Design of a Scalable, Flexible, and Durable Thermoelectric Cooling Device for Soft Electronics Using Kirigami Cut Patterns

A flexible, soft thermoelectric cooling device is presented that shows potential for human cooling applications in wearable technologies and close-to-body applications. Current developments lack integration feasibility due to non-scalable assembly procedures and unsuitable materials for comfortable and durable integration into products. Our devices have been created and tested around the need to conform to the human body which we have quantified through the creation of a repeatable drape testing procedure, a metric used in the textile industry. Inspired by mass manufacturing constraints, our flexible thermoelectric devices are created using commercially available materials and scalable processing techniques. Thermoelectric legs are embedded in a foam substrate to provide flexibility, while Kirigami-inspired cuts are patterned on the foam to provide the drape necessary for mimicking the performance of textile and close to body materials. In total, nine different configurations, three different fill factors and three different Kirigami cut patterns were fabricated and inspected for thermal characterization, mechanical testing, flexibility and drape. Our studies show that adding Kirigami patterns can increase the durability of the device, improve the flexibility, decrease the drape coefficient, and have <1% of impact on cooling performance at higher fill factors (>1.5%), reaching temperature differences up to 4.39 ± 0.17°C between the hot and cold faces of the device. These thermoelectric cooling devices show great flexibility, durability, and cooling for integration into soft cooling products.

Automation of Psychological Selection Procedures for Personnel to Specific Activities

The article presents a universal method for determining the professional suitability (PS) of a candidate and an algorithm for forming a psychological profile for a specific profession based on determining the psychological potential of personality. The developed method is based on the use of automated support systems. Based on the obtained value of the integral indicator, a decision is made on the PS group of this candidate. This method adapts to the requirements of the profession to candidates, taking into account changes in the conditions of activity by adjusting the typical psychological profile of the personality. The developed method for determining a candidate’s PS has been brought to practical implementation in the form of an Automated Psychodiagnostic Complex (APDC) “Psychodiagnostics.” APDC has been tested on the example of the psychological selection procedures of personnel for military service in units with law enforcement functions. APDС allows to reduce the time and labor costs for conducting psychodiagnostic studies, increases the reliability of tests due to a higher degree of standardization of the testing procedure, increases the accuracy of assessing psychological characteristics, and reduces the likelihood of errors in the processing of test results. APDС can be used for recruiting in various sectors of the economy, education, and military sphere.

Investigation of the adherence between clay blocks and grouts

This study aims to evaluate the adherence between clay blocks and grouts. For this purpose, push-out and pull-out tests were performed to assess the adherence presented by different combinations of five types of clay blocks and two types of grouts. The results demonstrated that the geometry of the cells of the clay blocks has a preponderant role in their adherence with grout, as the extent of the contact area between grout and block depends on the geometry of the cell. The shrinkage of the grout can cause the formation of cracks at the interface between block and grout, reducing the adherence between the materials. The shrinkage formed inside each type of block can be estimated based on the testing procedure developed in this research and used in conjunction with the geometric characteristics of the cells of the blocks to estimate the maximum load in the push-out tests. The test procedure developed to estimate the percentage of contact area lost due to grouts shrinkage shows to be promising, since its results were used in the equation to estimate the bond strength between blocks and grouts and shown good correlation. However, more study must be done because there are other variables that can affect the results. These results show that it is possible to use different characteristics of blocks and grouts to increase the adherence between these materials and provide a better behavior for reinforced masonry structures. However, it looks like if block types with a grooved hollow cell are used, a bigger contact surface is produced, and a higher bond strength appears to be assured.

Forward-Reverse Orthogonal Matching Pursuit-Union-Subspace Pursuit-Based Multiuser Detector for Uplink Grant-Free NOMA Networks

Multiuser Detection (MUD) is quite challenging in uplink grant-free non-orthogonal multiple access wireless communication networks in which users sporadically transmit data. The reason for this is that the base station (BS) must perform detection of both multiuser activity and user signals concurrently, because knowledge of user activity status is not available at the BS. In this paper, a new multiuser detector, named the Forward-Reverse Orthogonal Matching Pursuit–Union–Subspace pursuit (FROMPUS)-based MUD, is proposed. The detector takes advantage of the concept of an initial support set. This serves as initial knowledge that is then employed in the reconstruction of active users’ signals. In addition, the detector uses the “serial-include” technique of incorporating a likely support set element candidates and a reliability testing procedure in which the most prominent elements of the support set are selected. To assess the performance of the proposed detector, computer simulations are performed. The results obtained for various parameter settings show that the FROMPUS performs better than any of the other five detectors considered in this paper. However, this excellent performance comes with a slightly higher computational complexity cost. Nonetheless, the cost is inconsequential, since the detector operates at the BS where complexity is of low priority in comparison to performance.

Study of electrical circuits using Runge Kutta method of order 4

In this paper, Runge Kutta method of order 4 is used to study the electrical circuits designs through past, intermediate and present voltages. When integrating differential equations with Runge Kutta method of order 4, a constant step size (ℎ) is used until a testing procedure confirms that the discontinuity occurs in the present integration interval. This step size function calculations would take place at the end of the functional calculations, but before the dependent variables were updated. Runge Kutta methods along with convolution are given by array interpretation (Butcher matrix) representation, this leads to identify the equilibrium state. The input parameters indicate the voltage coefficient controlled by current sources and measures it a random periodic time. The output parameters provide stable independent values and calculated from past voltage and current values. Finally solutions are compared with exact values and RK method of order 4 along with Heun, Midpoint and Taylors’s method with various ℎ values.