The consistency and reliability of six-strand and four-strand flexor tendon repairs: a comparative porcine cadaveric study

The aim of this study was to compare the consistency and reliability of the six-strand Gan modification of the Lim-Tsai flexor tendon repair with the four-strand Adelaide repair, both with 3-0 sutures and with eight to ten runs of simple 5-0 running peripheral suture as well as the influence of the surgeons’ level of experience on the strength of the repair in a cadaveric animal setup. Thirty-nine surgeons repaired 78 porcine flexor digitorum profundus tendons with either the Adelaide technique (39 tendons) or the modified Lim-Tsai technique (39 tendons). Each repaired tendon was tested in a material testing machine under a single cycle load-to-failure test. The forces were recorded when the gap between the two tendon stumps reached 1 and 2 mm and when irreversible elongation or total rupture occurred. We found no significant differences in gap formation force and yielding strength of the tendons between the two methods. The surgeon’s previous experience in tendon repairs did not improve the consistency, reliability or tensile strength of the repairs. We conclude that if a strong peripheral suture is added, the modified Lim-Tsai repair has the same technical reliability and consistency as the Adelaide repair in term of ultimate loading strength in this test setup.

The study on the automated storage and retrieval system dependability

Automated storage systems have become the basis of warehouse logistics. The article presents a discussion on the reliability and dependability of Automated Storage and Retrieval Systems (ASRS), which are perceived as solutions with high technical reliability. Still, their role in the dependability of the entire warehouse system is to be discussed. The concepts of reliability and dependability in logistics systems like ASRS are defined, and a literature review in this area is presented. On this basis, the factors influencing the dependability of ASRS are discussed in a way not present in the discussion on this topic so far. Then, the ASRS simulation model (based on FlexSim simulation software) is presented. The model tests the influence of ASRS configuration and assigned resources on the dependability of the warehouse as a master system. The summary includes observations on defining the reliability and dependability of ASRS.

EVALUATION OF PV POWERED SWITCHABLE GLAZING TECHNOLOGIES IN TERMS OF THEIR SUITABILITY FOR OFFICE WINDOWS IN MODERATE CLIMATES

ABSTRACT In the search for façade solutions that meet requirements for energy efficiency and office space use comfort, it seems promising to apply a combination of photovoltaic (PV) technology with switchable glazing. It is believed that the merging of these two technologies might benefit the cooperation between regulated solar protection and energy efficiency. This article provides a design outlook on the use of PV-EC, PV-SPD, and PV-LCD technologies in terms of their utility for office buildings in moderate climates. This study concerns thermal, optical-visual, energetic, and technical issues, and a comparative method was applied. Based on current scientific research, the results of the analysis were juxtaposed with the requirements of the office working environment: natural lighting, thermal protection, glare protection, privacy control, energy efficiency, and technical reliability. The juxtaposition of these aspects revealed the advantages and disadvantages of a given solution from an architectural point of view. PV-EC technology in a side-by-side system was found to be the most appropriate solution and the results may be applied to make preliminary design decisions.

Methods for calculating the reliability of power supply systems

The aim was to determine the reliability indicators of a power supply system using an artificial neural network model. A model for calculating technical reliability was developed using the following methods: an algorithm for calculating reliability indicators of power supply systems, the method of failure rate of a power supply system and a forecasting model using artificial neural networks. It was established that a power supply system is formed by an open radial power supply circuit. The failure rate of the power supply subsystem was determined by calculating the failure rate of i-th element of the subsystem. As a result of calculating the probability of failure-free operation of the subsystem for various conditions (5 time intervals), it was found that with an increase in the operating time from 100 to 500 h, a linear increase in the rate of system failures occurs from 0.0051 to 0.0073 1/h. A comparison of the obtained mean-to-failure values of the main and the same backup subsystem in the unloaded mode with an absolutely reliable switch (269.62 h) with the main and the same backup subsystem in the loaded mode (202.21 h) was carried out. The results differ by 67.41 h, which indicates a higher degree of reliability of the first method. The software package Prognoz_INS_2020 was developed. An acceptable accuracy of no more than 2.17% was obtained by comparing the results of the conventional calculation of the failure rate of power supply systems and using the Prognoz_INS_2020 software package. This indicates the efficiency of the proposed software package in reliability calculations at operating energy enterprises. The proposed methods for assessing technical reliability both using the conventional model and a model based on an artificial neural network made it possible to assess the state of power supply systems, which helps to prevent dangerous emergencies.

Mechanotendography: description and evaluation of a novel method for investigating the physiological mechanical oscillations of tendons using a piezo-based measurement system

The mechanotendography (MTG) is a method for analyzing the mechanical oscillations of tendons during muscular actions. The aim of this investigation was to evaluate the technical reliability of a piezo-based measurement system used for MTG. The reliability measurements were performed by using audio samples played by a subwoofer. The thereby generated pressure waves were recorded by a piezo-based measurement system. An audio of 40 Hz sine oscillations and four different formerly in vivo recorded MTG-signals were converted into audio files and were used as test signals. Five trials with each audio were performed and one audio was used for repetition trials on another day. The signals’ correlation was estimated by Spearman (MCC) and intraclass correlation coefficients (ICC(3,1)), Cronbach’s alpha (CA) and by mean distances (MD). All parameters were compared between repetition and randomized matched signals. The repetition trials show high correlations (MCC: 0.86 ± 0.13, ICC: 0.89 ± 0.12, CA: 0.98 ± 0.03), low MD (0.03 ± 0.03V) and differ significantly from the randomized matched signals (MCC: 0.15 ± 0.10, ICC: 0.17 ± 0.09, CA: 0.37 ± 0.16, MD: 0.19 ± 0.01V) (p = 0.001 – 0.043). This speaks for an excellent reliability of the measurement system. Presuming the skin above superficial tendons oscillates adequately, we estimate this tool as valid for the application in musculoskeletal system.

Mechanotendography: description and evaluation of a novel method for investigating the physiological mechanical oscillations of tendons using a piezo-based measurement system

The mechanotendography (MTG) is a method for analyzing the mechanical oscillations of tendons during muscular actions. The aim of this investigation was to evaluate the technical reliability of a piezo-based measurement system used for MTG. The reliability measurements were performed by using audio samples played by a subwoofer. The thereby generated pressure waves were recorded by a piezo-based measurement system. An audio of 40 Hz sine oscillations and four different formerly in vivo recorded MTG-signals were converted into audio files and were used as test signals. Five trials with each audio were performed and one audio was used for repetition trials on another day. The signals’ correlation was estimated by Spearman (MCC) and intraclass correlation coefficients (ICC(3,1)), Cronbach’s alpha (CA) and by mean distances (MD). All parameters were compared between repetition and randomized matched signals. The repetition trials show high correlations (MCC: 0.86 ± 0.13, ICC: 0.89 ± 0.12, CA: 0.98 ± 0.03), low MD (0.03 ± 0.03V) and differ significantly from the randomized matched signals (MCC: 0.15 ± 0.10, ICC: 0.17 ± 0.09, CA: 0.37 ± 0.16, MD: 0.19 ± 0.01V) (p = 0.001 – 0.043). This speaks for an excellent reliability of the measurement system. Presuming the skin above superficial tendons oscillates adequately, we estimate this tool as valid for the application in musculoskeletal system.

Optimization Basics of Antiaircraft Defense System Building of Surface Ships Formation in Case of Anti-Ship Missiles Attacks Threat

The study proposed in the paper is aimed at determining the optimal (rational) parameters of building of an antiaircraft defense (AD) system of surface ships formation in case of anti-ship missiles attacks threat, namely: bearings and distances of the сore ships location and escort ships in the AD formations, taking into account the restrictions associated with the accomplishment of assigned combat missions, the target allocation of antiaircraft fire weapons of ships, both collective defense and self-defense, when repelling AShM attacks, combat readiness modes of the AFW, taking into account their technical reliability and duty schedule in the interests of AD, sectors of the combat use of electronic warfare, taking into account the electromagnetic compatibility (EMC) with the used AFW, orientation sectors of fighter aviation taking into account the compliance with security measures when using together with AFW. The multicriteria optimization methods using for the developed simulation model of the AD system functioning of surface ships formation in case of the AShM attacks threat in the specific conditions of the tactical situation allows obtaining the necessary practical recommendations on the ships formation in the AD formation, designation of combat readiness modes, duty schedule and the organization of the combat using of AFW, EW facilities, FA orientation in the case of the attack threat and the direct repelling of AShM attacks from one or several directions, it corresponds to the building of an equal-strength antiaircraft fire covering system, considering the available composition of the forces and AD facilities of the formation ships.

RESEARCH OF ORGANIZATION OF SUPPLY CHAIN MANAGEMENT TO MAINTAIN THE FUNCTIONALITY OF AVIONIC EQUIPMENT

The article reveals the issues of replacing spare serviceable devices (spare parts) for avionics objects for aircraft, discusses the organization and construction of supply chains, discusses the features of the functioning of avionics objects and their repair. The necessity of including blocks for modeling various scenarios of supply chains into the decision-making loop for the assembly and launch of spare devices is substantiated. Particular attention is paid to the classification of methods for calculating spare parts, based on the theory of restoration processes. The graphs of the function of increasing the functioning of avionics objects, graphs of the reliability of objects and graphs of forecasting the number of deliveries are given. The article discusses the possibilities of organizing supplies and their unique features. The necessity of modeling various delivery options and the limited data obtained on the basis of standard parameters, which include the technical reliability of the parameters of specific devices, are proved. Key words: SPTA, avionics, instrument, supply chain, aviation instrument reliability.