Minimum Components Research Articles

Design of a Double-Sided LCLC-Compensated Capacitive Power Transfer System With Predesigned Coupler Plate Voltage Stresses

A high-performance capacitive power transfer (CPT) system is expected to achieve the load-independent constant output, near-zero reactive power, and soft switching of power switches simultaneously, resulting in a reduced power stage, simple control circuitry, and minimum component ratings. However, a well-compensated CPT system still suffers very-high-voltage stresses among not only the main coupled plates but also the leakage coupled plates due to the small coupling and edge emission, which increases the risk of air breakdown and deteriorate the electromagnetic interference (EMI) issue. To solve this problem, the voltage stresses among such coupler plates should be predesigned at an acceptable level. This article systematically analyzes the characteristics of a double-sided <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$LCLC$ </tex-math></inline-formula> -compensated CPT converter that is proven to have enough design freedom providing predesigned voltage stresses for two kinds of coupled plates. Also, three operating frequencies with load-independent constant current (CC) output and input zero-phase angle (ZPA) are found. Without reactive power in the circuit, a parameter design method is proposed for the double-sided <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$LCLC$ </tex-math></inline-formula> -compensated CPT converter at each frequency to satisfy the desired CC output and the predesigned voltage limitations. In this way, the breakdown and EMI issues can be well mitigated by the intended design, and this method can also be extended to other CPT circuits. Finally, a CPT prototype is built to verify the theoretical analysis with the predesigned voltage stresses among the coupler plates.

Anomaly Detection Framework in Fog-to-Things Communication for Industrial Internet of Things

The rapid development of the Internet of Things (IoT) in the industrial domain has led to the new term the Industrial Internet of Things (IIoT). The IIoT includes several devices, applications, and services that connect the physical and virtual space in order to provide smart, cost-effective, and scalable systems. Although the IIoT has been deployed and integrated into a wide range of industrial control systems, preserving security and privacy of such a technology remains a big challenge. An anomaly-based Intrusion Detection System (IDS) can be an effective security solution for maintaining the confidentiality, integrity, and availability of data transmitted in IIoT environments. In this paper, we propose an intelligent anomaly-based IDS framework in the context of fog-to-things communications to decentralize the cloud-based security solution into a distributed architecture (fog nodes) near the edge of the data source. The anomaly detection system utilizes minimum redundancy maximum relevance and principal component analysis as the featured engineering methods to select the most important features, reduce the data dimensionality, and improve detection performance. In the classification stage, anomaly-based ensemble learning techniques such as bagging, LPBoost, RUSBoost, and Adaboost models are implemented to determine whether a given flow of traffic is normal or malicious. To validate the effectiveness and robustness of our proposed model, we evaluate our anomaly detection approach on a new driven IIoT dataset called X-IIoTID, which includes new IIoT protocols, various cyberattack scenarios, and different attack protocols. The experimental results demonstrated that our proposed anomaly detection method achieved a higher accuracy rate of 99.91% and a reduced false alarm rate of 0.1% compared to other recently proposed techniques.

Korišćenje strujnog senzora ACS712 baziranog na Holovom efektu za merenje jačine elektične struje u kolima energetske elektronike

Current measurement in power electronic systems is a necessary part of the measurement process. There are different ways for current measurement like using current transformers or using the Rogowski coils which are not precise enough in many applications and not suitable for use in power electronic measurement systems. For that reason, the Hall effect-based sensor can be used as a very precise alternative with minimum external components. Presented in this paper is utilizing the Hall effect current sensor ACS712 for current measurement with a microcontroller system. The measurement with the Hall effect sensor is described with an appropriate comparison of the measurement values on a microcontroller system and multimeter and high precision power analyzer Chauvin Arnoux 8335.

Bridgeless Isolated Positive Output Luo Converter Based High Power Factor Single Stage Charging Solution for Light Electric Vehicles

In this article, a high-power factor ac–dc conversion system based on bridgeless isolated positive output Luo converter is demonstrated for light electric vehicles charging. Unlike conventional bridgeless Luo converters, the presented topology ensures positive voltage polarity at its output and incorporates a minimum component count over the universal supply voltage range of 85 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> to 265 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> . Meanwhile, the volume of magnetic components and the charger's cost are reduced by considering a discontinuous inductor current mode (DICM) design. To accomplish desired charging profile of the battery, a simple control incorporating few sensing devices and single gate drive circuitry, is utilized. It is noteworthy that, the single stage bridgeless structure of the presented topology with DICM design considerably reduces conduction and switching losses of the charger. Finally, the presented topology is designed and modeled through MATLAB environment, and its efficacy is tested through a prototype in the laboratory environment. The critical test results at various operating conditions are demonstrated to verify design and control objectives of the charger. A brief comparative analysis with existing solutions, is presented to justify the effectiveness of the presented solution.

The Roadmap for Implementing Value-Based Healthcare in European University Hospitals—Consensus Report and Recommendations

ObjectivesValue-based healthcare (VBHC) aims at improving patient outcomes while optimizing the use of hospitals’ resources among medical personnel, administrations, and support services through an evidence-based, collaborative approach. In this article, we present a blueprint for the implementation of VBHC in hospitals, based on our experience as members of the European University Hospital Alliance. MethodsThe European University Hospital Alliance is a consortium of 9 large hospitals in Europe and aims at increasing the quality and efficiency of care to ultimately drive better outcomes for patients. ResultsThe blueprint describes how to prepare hospitals for VBHC implementation; analyzes gaps, barriers, and facilitators; and explores the most effective ways to turn patient pathways into a process that results in high-value care. Using a patient-centric approach, we identified 4 core minimum components that must be established as cornerstones and 7 organizational enablers to waive the barriers to implementation and ensure sustainability. ConclusionThe blueprint guides through pathway implementation and establishment of key performance indicators in 6 phases, which hospitals can tailor to their current status on their way to implement VBHC.

Failure Mode Determination of American Petroleum Institute 12F Shop-Welded Tanks With a New Roof-to-Shell Junction Detail

Abstract The American Petroleum Institute (API) 12F is the specification for vertical, aboveground shop-welded storage tanks published by the API. The nominal capacity for the twelve tank designs given in the current 13th edition of API 12F ranges from 90 bbl. (14.3 m3) to 1000 bbl. (159 m3). The minimum required component thickness and design pressure levels are also provided in the latest edition. This study is a part of a series research project sponsored by API that dedicates to ensure the safe operation of API 12 series storage tanks. In this study, the twelve API 12F tank designs presented in the latest edition are studied. The elastic stress analysis was conducted following the procedures presented in the ASME Boiler and Pressure Vessel Code 2019, Section VIII, Division 2 (ASME VIII-2). The stress levels at the top, bottom, and cleanout junctions subject to the design pressures are determined through finite element analysis (FEA). The bottom uplift subjected to design pressures are obtained, and the yielding pressure at the roof-shell and shell-bottom junctions are also determined. The specific gravity of the stored liquid is raised from 1.0 to 1.2 in this study. A new roof-shell attachment detail is proposed, and a 0.01 in. (0.254 mm) gap between the bottom shell course and the bottom plate is modeled to simulate the actual construction details. In addition, the flat-top rectangular cleanout presented in the current edition of API 12F is modeled. Moreover, various thickness combinations are considered to further investigate the effect due to different component thicknesses.

Synthesis of DC–DC Converters From Voltage Conversion Ratio and Prescribed Requirements

This article proposes a systematic synthesis method to identify the optimum converter topology for a specified voltage conversion ratio. This gain-oriented converter synthesis is formulated as an inverse problem around the inductor flux balance equations. The proposed synthesis method consists of two processes. A set of distinct converter topologies is first synthesized from the specified voltage conversion ratio by obtaining the solutions for a set of six inverse equations in twelve unknowns. The optimal topology for any intended application can be identified based on the desired performance metrics. The complete synthesis method is illustrated with quadratic buck-boost gain as an example. In total, 25 distinct topologies are synthesized using the first process, and their feasibility is validated by PLECS simulation. In total, three case studies are reported to explain the second process. Ground-referenced output and the minimum number of switches are used as the first two selection criteria in all the case studies. Minimum peak inductor current, minimum component stress factor, and minimum voltage and current stress are the third selection criterion in Case Studies-1, 2, and 3, respectively. The steady-state operations of two optimal converters selected in Case Study-1 were verified experimentally.

Influence of socioeconomic status on oral disease burden: a population-based study

BackgroundDental caries is associated with Biological, behavioral, socioeconomic, and environmental factors; however, socioeconomic status is a distal determinant of dental caries development that modulates exposure to risk and protective factors. This study aimed to analyze the socioeconomic factors associated with the concentration of oral diseases in a population-based study in Brazil.MethodsThis is a quantitative, analytical, cross-sectional study based on secondary data from the SB São Paulo 2015 epidemiological survey. A total of 17,560 subjects were included. The concentration of oral disease in the population was estimated by the oral disease burden (ODB) variable. The ODB consists of four components: dental caries; tooth loss; need for dental prosthesis and periodontal condition. Thus, the total score on the ODB could vary between 0 and 4, with the highest score indicating the worst possible situation. ODB was analyzed in multivariate negative binomial regression, and multivariate binary logistic regression analysis. The following factors were included as independent variables: age group, skin color, socioeconomic factors, family income and Oral Impact on Daily Performance (OIDP).ResultsIn the sample, 86.9% had no minimum ODP component. Negative multivariate binomial regression showed a statistically significant relationship (p < 0.005) between ODB and all variables analyzed (skin color, family income, education, OIDP results and age range). The adjusted multivariate binary logistic regression showed that the individuals most likely to have at least one component of ODB were nonwhite (25.5%), had a family income of up to R$ 1500.00/month (19.6%), had only completed primary education (19.1%), and reported that their oral health had an impact on their daily activities (57.6%). Older adults individuals were two times more likely than adolescents to have an ODB component.ConclusionsODB is associated with factors related to social inequality. Adults and older adults individuals had the highest cumulative number of ODB components.

A new murine esophageal organoid culture method and organoid-based model of esophageal squamous cell neoplasia

SummaryOrganoids mimic the physiologic and pathologic events of organs. However, no consensus on esophageal organoid (EO) culture methods has been reached. Moreover, organoid models reproducing esophageal squamous cell carcinoma (ESCC) initiation have been unavailable. Herein, we sought to develop an esophageal minimum essential organoid culture medium (E-MEOM) for culturing murine EOs and establishing an early ESCC model. We formulated E-MEOM to grow EOs from a single cell with clonal expansion, maintenance, and passage. We found that EOs cultured in E-MEOM were equivalent to the esophageal epithelium by histological analysis and transcriptomic study. Trp53 knockout and KrasG12D expression in EOs induced the development of esophageal squamous neoplasia, an early lesion of ESCC. Here we propose the new formula for EO culture with minimum components and the organoid model recapitulating ESCC initiation, laying the foundation for ESCC research and drug discovery.

Concept Design and Analysis of the Magnet System of the Sustained High Power Density Tokamak Facility

A recent National Academy study recommended a next-step sustained high power density (SHPD) facility for the United States that can be a bridge to a compact fusion pilot plant. A design has been initiated to investigate a possible SHPD non-deuterium-tritium device that builds upon recent low aspect ratio tokamak studies. A 1.2-m device with a 2.4 aspect ratio has been chosen to evaluate physics performance goals within a double-null plasma machine arrangement centered on three component features: high current density toroidal field (TF) and central ohmic heating/poloidal field (PF) coils, liquid metal divertor/first wall systems, and the integration of a limited set of outboard dual-coolant lead lithium test blankets that can be maintained within a vertical maintenance approach. The underlying initiative of the U.S. program is to promote research and technology advancements that lead to the construction of a compact pilot plant that produces electricity from fusion at the lowest possible capital cost. High-field, higher power density will bring down the size of a fusion device and can lower the cost, but this can only occur with the development of high-current density TF and PF windings, a support system to handle the higher magnetic loads, and a cost structure that is economically viable. High-temperature superconductors (HTSs) offer the potential to meet high-field/high-current requirements and is under development by a number of institutions. Fabrication process improvement would continue to bring down the price if a market for fusion devices were to develop and the production level of HTS cable were to increase; however, this is not happening with any expedience especially related to fusion applications. At present, HTS conductors are an order of magnitude more expensive than low-temperature superconductors (LTSs), making an early application for a near-term SHPD experimental device problematic, especially for a low aspect ratio design that has minimum component space within the device inboard region. In lieu of an HTS-based, high-current density TF winding design, a moderately high-current density winding design (>80 MA/m2) based on cable-in-conduit LTS conductors in a multiwinding pack arrangement sized for low and high field was defined. This paper focuses on the design of the magnet system, with attention given to the analysis performed on the SHPD TF casing structure. The analysis is carried out for various sections: (1) Emag analysis of the SHPD structure, (2) TF casing winding pack evaluation for TF-TF self-load only with slit model and three-dimensional geometry, (3) effect of the shear pin in the TF casing structure, and (4) compression ring effect on the SHPD structure.

Bivalent copper oligopyrocatecholate as a novel heterogeneous catalyst for the oxidative degradation of mercaptan in caustic solution: Synthesis, characterization, and kinetic study

A novel catalyst based on bivalent copper oligopyrocatecholate was first successfully synthesized and dispersed in a polymer matrix for oxidative degradation of mercaptan in aqueous caustic solution. X-ray diffraction analysis has demonstrated that the synthesized catalyst was a crystalline phase with a minimum amorphous component. Mechanism analysis and kinetic experiments were conducted to investigate the kinetic mechanism of the reaction of isopropyl mercaptan oxidation catalyzed by copper oligopyrocatecholate dispersed in a polymer matrix. The influences of temperature, initial concentrations of reactants, and catalytic surface area on the reaction rate were studied to obtain the rate expression of intrinsic kinetics. The research results showed that the subsequent electron-transfer step was the rate-limiting step of the reaction. Additionally, the mercaptan oxidation rate in caustic solution was inversely proportional to the first power of the alkali concentration. The apparent activation energy was approximately 27.71 ± 1.12 kJ/mol. Importantly, this rate law for mercaptan oxidation can be used to design industrial reactors for the light oil sweetening process.

Novel VDBA based universal filter topologies with minimum passive components

In this research, voltage differencing buffered amplifier (VDBA) is utilized in designing three novel multi-input single output (MISO) topologies of universal filters. The designed filters employ minimum number of passive components and did not require any passive component matching condition. Two of the designed filters can work in dual mode of operation simultaneously. The designed filters have inbuilt tunability property. The nonideal gain analysis and sensitivity analysis of the filters are also carried out to study the effect of process variations and process spread on the filter responses. The complete layout of the VDBA is designed using 0.18μm Silterra Malaysia process design kit (PDK) in Cadence design software. The parasitic extraction is done using Mentor graphics Calibre tool. The postlayout simulations bear close resemblance with the theoretical predictions.

A multiple-relaxation-time collision model by Hermite expansion

The Bhatnagar-Gross-Krook (BGK) single-relaxation-time collision model for the Boltzmann equation serves as the foundation of the lattice BGK (LBGK) method developed in recent years. The description of the collision as a uniform relaxation process of the distribution function towards its equilibrium is, in many scenarios, simplistic. Based on a previous series of papers, we present a collision model formulated as independent relaxations of the irreducible components of the Hermite coefficients in the reference frame moving with the fluid. These components, corresponding to the irreducible representation of the rotation group, are the minimum tensor components that can be separately relaxed without violating rotation symmetry. For the 2nd, 3rd and 4th moments, respectively, two, two and three independent relaxation rates can exist, giving rise to the shear and bulk viscosity, thermal diffusivity and some high-order relaxation process not explicitly manifested in the Navier-Stokes-Fourier equations. Using the binomial transform, the Hermite coefficients are evaluated in the absolute frame to avoid the numerical dissipation introduced by interpolation. Extensive numerical verification is also provided. This article is part of the theme issue 'Progress in mesoscale methods for fluid dynamics simulation'.

Electro-Magnetic and Structural Analysis of Six-Pole Hybrid-Excited Permanent Magnet Motors

Potentials and limits of the Hybrid-Excitation Permanent-Magnet (HEPM) synchronous machine are dealt with in this paper. A six-pole machine is taken into consideration, and both parallel and series configurations are analysed and compared. Taking advantage of the rotor excitation coils, the permanent magnet (PM) rotor flux can be adjusted according to the operating speed to improve its performance parameters. The electro-magnetic force is analysed in its first harmonic and in the complete shape. Moreover, a comparison between analytical and numerical formulation has been done for the rotor current control. In particular, the speed range is extended, and electro-mechanical torque and power are increased, as well as the efficiency. It will be shown that the rotor flux reduction by using the excitation winding yields an improvement of the motor performance. The main advantage will be obtained during the flux-weakening operations. In this paper, different rotor topologies will be analysed to highlight the advantages and drawbacks of each of them, and how it is possible to achieve higher speed with higher torque and without high saliency ratio. A magnetic network will be introduced to explain the different contribution of the excitation winding to the rotor flux. Furthermore, a comparison of the amount of the volume of PM, copper and iron in internal permanent magnet (IPM) motor and HEPM motor will be analysed. Actually, an analysis of the harmonic content in the electro-motive force even varying the excitation current and a mechanical stress analysis of each machine will be shown. Finally, it will be verified that the excitation losses represent a minimum component of the total losses.

Impact of different fuel usages on thermodynamic performances of a high bypass turbofan engine used in commercial aircraft

In this study, energy, exergy, and sustainability analyses are performed for the PW4056 engine to observe the different fuel effects on the thermodynamic performance of a turbofan engine. For this purpose, energy and exergy analyses are performed at the same dead state conditions, and then sustainability analyses are conducted for kerosene and hydrogen-powered engine and its main components. Also, nineteen thermodynamic performance metrics are adapted for the purpose of the study and used to compare the fuel performances. It is found that the fuel mass flow of the hydrogen fuel (1.03 kg/s) is lower than the kerosene fuel (2.85 kg/s), the exhaust gases mass flow of the hydrogen fuel (117.14 kg/s) is lower than the kerosene fuel (118.96 kg/s). The minimum exergy efficient component is determined as the combustion chamber in both cases, which are 64.24 % for kerosene case and 58.20 % for hydrogen case. The lowest relative exergy loss ratio is calculated to be 28.28 % for Fan outlet loss for hydrogen case, while the maximum relative exergy consumption ratio is calculated to be 51.93 % for combustion chamber for hydrogen case. The maximum productivity lack ratio is computed as 161.65 % for combustion chamber for hydrogen case, whereas the minimum relative fuel exergy waste ratio is computed as 0.02 % for high pressure turbine for hydrogen case, The highest exergetic improvement potential rate is obtained to be 24231.48 kW for combustion chamber for hydrogen case, while the lowest product ratio indicator is found to be 17.03 % for low pressure compressor for kerosene case. Furthermore, the minimum exergetic sustainability index is obtained to be 1.39 for the combustion chamber for the hydrogen case, whereas the maximum environmental effect factor is obtained to be 0.72 for combustion chamber for hydrogen case. On the other hand, with the usage of hydrogen fuel; it is observed that the exergy efficiency of the overall engine decreases from 26.9 % to 24.3 %, the ecological effect factor of the overall engine goes up from 3.712 to 4.113, the exergetic sustainability index of the overall engine rises from 0.321 to 0.369, and the waste exergy cost flow of the overall engine increases from 17.41 × 10 −3 US$/kW to 19.09 × 10 −3 US$/kW.

Increasing Gene Editing Efficiency for CRISPR-Cas9 by Small RNAs in Pluripotent Stem Cells.

Gene manipulations of human induced pluripotent stem cells (iPSCs) by CRISPR-Cas9 genome engineering are widely used for disease modeling and regenerative medicine applications. There are two competing pathways, non-homologous end joining (NHEJ) and homology directed repair (HDR) that correct the double-strand break generated by CRISPR-Cas9. Here, we improved gene editing efficiency of gene knock-in (KI) in iPSCs with minimum components by manipulating the Cas9 expression vector. Either we inserted short hairpin RNA expression cassettes to downregulate DNAPK and XRCC4, two main players of the NHEJ pathway, or we increased cell survival by inserting an anti-apoptotic expression cassette of miRNA-21 into the Cas9 vector. For an easy readout, the pluripotency gene SOX2 was targeted with a T2A-tdTomato reporter construct. In vitro downregulating DNAPK and XRCC4 increased the targeting efficiency of SOX2 KI by around twofold. Furthermore, co-expression of miRNA-21 and Cas9 improved the efficiency of SOX2 KI by around threefold. Altogether, our strategies provide a simple and valuable approach for efficient CRISPR-Cas9 gene editing in iPSCs.

Deficit Irrigation-Nutrient Coupling on Growth, Yield, Fruit Quality and Water Use Efficiency of Indian Jujube

Sustainability of quality fruit production in Indian jujube is adversely affected by improper irrigation and nutrient management. A field study comprising of four irrigation levels (drip irrigation at 0.8, 0.6 and 0.4 of pan evaporation (E0) and surface irrigation at 1.0 IW/CPE with 50 mm depth) and three nutrient levels (100% RDF, 75% RDF+25% RDF as vermicompost and 50% RDF+50% RDF as vermicompost) was conducted during 2018-19 (11 months) on jujube plant. Results showed that tallest tree (3.72 m), greatest tree circumference (0.32 m), maximum fruits tree-1 (563), highest fruit weight (15.5 g) and fruit yield tree-1 (8.42 kg) were recorded with drip irrigation at 0.8 E0 with 100% RDF. Minimum growth, yield components and yield were found with drip irrigation at 0.4 E0 with 50% RDF+50% RDF as vermicompost. Seasonal ETa was 373.6, 409.4 and 446.4 mm for drip irrigation at 0.4, 0.6 and 0.8 E0, respectively and 694 mm for surface irrigation. Maximum CWUE of 18.87 g tree-1 mm-1 was obtained with drip irrigation at 0.8 E0 with 100% RDF. About 55.7-75.5% water was saved by drip irrigations which could bring an additional area of 55.5-85.8% under drip irrigated jujube. Highest predicted yield of 9.02 kg tree-1 was accomplished with 278 mm irrigation water. This model approach could serve as a good guideline to yield potential decision in relation to limited irrigation water for jujube growers in the Indo-Gangetic plains or similar agro-climatic regions.

Diagnostic accuracy of ultrasound shear wave elastography combined with superb microvascular imaging for breast tumors: A protocol for systematic review and meta-analysis.

Background:Shear wave elastography (SWE) is a new ultrasonic elastography technique for evaluating the hardness of living tissue by measuring the propagation velocity of shear wave in tissue, which is characterized by real-time, non-invasive and quantitative. The SWE technique can be used to diagnose the lesions of different tissues and organs, and the quantitative measurement of SWE is considered as more objective information about breast masses. Superb microvascular imaging (SMI) is a new noninvasive Doppler ultrasound imaging method, which can display blood flow information with high spatial resolution and high frame rate, while keeping the minimum low-speed blood flow components. Therefore, SMI can diagnose diseases closely related to angiogenesis at a relatively early stage. However, the results of these studies have been contradictory. The present meta-analysis aimed at determining the accuracy of SWE combined with SMI in the differential diagnosis between benign and malignant breast lesions.Methods:We will search PubMed, Web of Science, Cochrane Library, and Chinese biomedical databases from their inceptions to the April 18, 2021, without language restrictions. Two authors will independently carry out searching literature records, scanning titles and abstracts, full texts, collecting data, and assessing risk of bias. Review Manager 5.2 and Stata14. 0 software will be used for data analysis.Results:This systematic review will determine the accuracy of shear wave elastography combined with superb microvascular imaging in the differential diagnosis between benign and malignant breast tumors.Conclusion:Its findings will provide helpful evidence for the accuracy of shear wave elastography combined with superb microvascular imaging in the differential diagnosis between benign and malignant breast tumors.Systematic review registration:INPLASY202150075

Research of the Photo-Optical Method Application for Measuring Selected Data on the Movement of a Parachute for Type M-282

Testing in the field of parachute technology provides space for the application of new and innovative methods of measuring operating and functional parameters. The main aim of the paper is to present the results of research for the verification of the photo-optical method of measuring the vertical speed of the M-282 parachutes, and for its use in testing, collecting, and investigating motion data in parachuting. As part of this measuring technology, twelve jumps were performed. It was verified that the experiment was completed for the M-282 parachute according to the regulation of SAE AS 8015B “Minimum Performance Standard Parachute Assemblies and Components”. An analysis of the influencing factors and quantification of their influence on the uncertainty of the measurement results was also performed. The results of the measurement achieved by using the photo-optical method were compared with the measurement with the electronic variometer FLYTEC 4030. The vertical speed of the M-282 parachute (4.655 m·s−1) defined by the photo-optical method is significantly similar to the vertical speed of the M-282 parachute (4.662 m·s−1) defined by FLYTEC 4030. We can state that the process of identifying the vertical speed of the parachute by the photo-optical method was correct. This is a suitable method of evaluating motion data in the operation of M-282 type parachutes. In the following research for generalization of the methodology, we assume the performance of more than 60 experimental jumps using different types of parachutes, digital sensors (cameras), and a photo-optical method to examine motion data and formulate recommendations for testing, investigative applications, individualized training programs, and aspects of parachuting injury prevention.

Comparison of Various Criteria Determining the Direction of Crack Propagation Using the UDMGINI User Procedure Implemented in Abaqus.

This paper describes a method of predicting the direction of crack propagation implemented by user subroutines in the Simulia-Abaqus FEA system with the use of the extended finite element method (X-FEM). This method is based on displacements and stresses according to Westergaard’s solution of Griffith’s crack problem. During the calculations, in each crack increment, the algorithm reads the stresses and displacements in the model around the crack tip, calculates the criterion values at the read points, reduces them to a unit distance from the crack tip, fits a polynomial to these points, and finds the minimum of the function closest to the last propagation angle. The algorithm also decides when the crack grows, depending on a chosen criterion. Four criteria have been implemented to predict the direction of failure propagation: the maximum principal stress criterion, the Ottosen–Podgórski criterion, the new criterion described here based on the minimum component values of the displacement vector, and the maximum circumferential tensile stress (MTS). These criteria were verified in two tests: the three-point bending test of the notched beam and the anchor pull-out test. For these tests, the criterion built into Simulia Abaqus does not correctly define the crack path, which causes the crack propagation direction to “rotate” when simulating the fracture. The criteria developed here, in most cases, determine the crack path and the maximum force very well compared to real laboratory tests.