Important Protective Device Research Articles

Optimal parameters of protection devices for controlling hydraulic transient using genetic algorithms

Abstract Air valves and pressure vessels are among the most important protection devices used to protect the main pumping lines due to their reliability in controlling transient pressures. The proper and rational design of the water hammer protection devices ensures high efficiency in controlling the values of transient pressures in addition to achieving acceptable cost. For this purpose, the genetic algorithm approach was adopted in the process of selecting the optimal parameters for both pressure vessels (size and orifice diameter) and air valves (orifice diameter of inlet and outlet, discharge coefficients of inlet and outlet) in addition to determining the type and location of the air valve. The performance of the proposed protection devices was verified by comparing three objective equations: (1) minimizing the cost of protection devices, (2) minimizing the difference between the maximum and minimum pressure, and (3) minimizing the difference between the maximum and minimum pressure with a specific constraint on the budget of protection devices. The study results showed that selecting the optimal design parameters for pressure vessels and air valves helps control the cost of protection devices and transient pressure values.

A novel bio-inspired helmet with auxetic lattice liners for mitigating traumatic brain injury

The human head is most vulnerable to injury during activities such as road traffic and sports. To mitigate the risk of traumatic brain injury (TBI), helmets serve as an important protective device. This study proposes a hedgehog biomimetic helmet with auxetic lattice liners in the shape of a hemisphere. The helmeted head impact configuration is built based on a high bio-fidelity head-neck finite element model incorporated into our novel helmet model. Biomechanical responses including acceleration, intracranial pressure, and von Mises strain of head are extracted from the simulation model to assess TBI risks. The results indicate that the helmet featuring auxetic lattice liners outperforms those without liners or with other liner designs, offering superior protection. Compared to the threshold, the novel helmet design was found to reduce the head injury criterion value by 72.65%. Additionally, parametric studies of lattice’s bar radius for uniform and graded auxetic lattice liners are discussed. Finally, this study also carries out the optimization design of lattice strut radius and height, resulting in a lightweight auxetic lattice liner with superior protective performance. The outcomes of this study extend the application of auxetic materials and provide guidance for designing helmet liners that better mitigate TBI.

금융소비자보호법상 보험상품의 설명의무와 그 위반의 효과

In general, sales of insurance products are not only made in the form of conforming contracts that depend on terms and conditions, but also there is a risk of damage to the policy holder due to information asymmetry and incompatibility of status between the parties to the contract, and thus in order to improve the fairness and equity of contracts, various safeguards are being prepared for them. Among these, the most important protection device is the insurer's duty of explanation.
 Therefore, the Commercial Act and other special laws stipulate various obligations of explanation in order to protect policy holders when signing and transferring insurance contracts, and in particular, the obligation to explain terms and conditions and the obligation to explain insurance products are separately regulated. In other words, Article 638-3 of the Commercial Act and Article 3 of the Terms and Conditions Regulation Act give the insurer the duty to deliver and explain the terms and conditions, and the recently enacted Article 19 of the Financial Consumer Protection Act separately and specially imposes the duty to explain important details of insurance products.
 In this paper, while comparing and analyzing the relationship between these regulations, the obligation to explain insurance products under the Financial Consumer Protection Act was reviewed and the effect of the violation was considered. In particular, regarding the problem of the right to withdraw subscription and the right to terminate an illegal contract as an effect of violation of duty of explanation, legislative alternatives were sought, focusing on the following issues.
 First, after the duty of explanation under the Insurance Business Act was transferred to the Financial Consumer Protection Act, what characteristics the “duty to explain” of insurance products under the Financial Consumer Protection Act compared to the duty of explanation under the Commercial Act and the Contract Regulations Act were analyzed. And among the effects of violation of duty of explanation, the problem of the right to withdraw subscription and the right to terminate illegal contract was identified and a solution was derived.
 Second, it was examined what is the characteristics and differences in the exercise requirements and effects of “the right to withdraw subscription” and “the right to terminate illegal contracts” due to violation of the duty to explain insurance products under the Financial Consumer Protection Act compared to the legal effects of the general legal principles of the Civil Act, such as the right to withdraw, the right to cancel, and the right to terminate. In addition, in the application to insurance practice, what kind of collision problems occur between these regulations was examined, the root cause was identified, and improvement measures were prepared.

Research of ZnO Arrester Deterioration Mechanism Based on Electrical Performance and Micro Material Test

The traction power supply system of an Electrical Multiple Unit (EMU) often suffers from overvoltage impact. As an important protection device for on-board electrical equipment, the working environment of a roof arrester is worse than that of a power system. In recent years, the explosion failure of the roof arresters of an EMU has occurred from time to time, which seriously endangers the safe operation of high-speed railways. In this paper, the electrical performance test and material micro test of roof arrester in three states of normal, defect, and exploded, are carried out in order to study the internal causes of roof arrester explosion and clarify its deterioration mechanism. Using the DC reference voltage test and leakage current test, the electrical performance differences of normal, defective, and exploded arresters are obtained. By studying the disassembly of an arrester, the appearance characteristics of arrester varistor in three states are obtained. The micro morphology and chemical elements of the varistor are analyzed by Scanning Electron Microscope and Energy Dispersive Spectrometer. The deterioration mechanism of the arrester varistor is then revealed, and preventive measures for the explosion failure of the roof arrester are put forward. The obtained results show that, during the long-term operation of the roof arrester of an EMU, the varistor may be damp, and therefore the aluminum electrode layer and side insulation layer of the varistor may deteriorate. After the deterioration of the aluminum electrode layer, the content of the O element increases, and multiple film structures are formed on the surface. After the deterioration of the side insulating layer, the content of the O element increases, and the surface becomes uneven. Improving the sealing performance requirements of the roof arrester and optimizing the maintenance process can reduce its explosion failure.

Impact of ultraviolet germicidal irradiation on new silicone half-piece elastometric respirator (VJR-NMU) performance, structural integrity and sterility during the COVID-19 pandemic

Since the innovation of our new half-piece elastometric respirator, this type of filtering facepiece respirator (FFR) has been used widely in Thailand. Decontamination methods including ultraviolet C (UVC) germicidal irradiation and 70% alcohol have been implemented to decontaminate these respirators. We then examined the inactivation potential of different decontamination processes on porcine epidemic diarrhea virus (PEDV) and numerous bacterial strains, most of which were skin-derived. To enable rigorous integrity of the masks after repeated decontamination processes, fit tests by the Bitrex test, tensile strength and elongation at break were also evaluated. Our results showed that UVC irradiation at a dose of 3 J/cm2 can eradicate bacteria after 60 min and viruses after 10 min. No fungi were found on the mask surface before decontamination. The good fit test results, tensile strength and elongation at break were still maintained after multiple cycles of decontamination. No evidence of physical degradation was found by gross visual inspection. Alcohol (70%) is also an easy and effective way to eradicate microorganisms on respirators. As the current pandemic is expected to continue for months to years, the need to supply adequate reserves of personnel protective equipment (PPE) and develop effective PPE reprocessing methods is crucial. Our studies demonstrated that the novel silicone mask can be safely reprocessed and decontaminated for many cycles by UVC irradiation, which will help ameliorate the shortage of important protective devices in the COVID-19 pandemic era.

Response Characteristics of Gas Discharge Tube to High-Power Microwave

Gas discharge tube (GDT), as an important protective device, has been developed and employed for the protection of circuit against high-power electromagnetic energy. Accurate description of the protective property of GDT is critical for its practical applications. However, under the excitation of high-power microwave (HPM), how the GDT will respond and whether the GDT can still exhibit protective performance remain unclear. Herein, the response characteristics of GDT to HPM were studied in this article. With the increment of excitation voltage, the response time of GDT decreases exponentially, and eventually reaching about 10 ns. The suppression ratio to HPM energy can attain 90%. The dynamic breakdown voltage and arc-mode voltage continuously increase as the excitation voltage is increased. Specifically, the arc-mode voltage nearly exhibits a linearly increasing trend. Moreover, the response property of GDT to HPM was simulated by using a PSpice model. The simulations are in good agreement with the experimental results, indicating the model can be used for predicting the behaviors of GDT under the excitation of HPM.

Performance validation and dynamic response analysis of a deepwater cable bending restrictor

The deepwater cable bending restrictor is an important protective device for risers, umbilicals and cables in offshore engineering, protecting cable structure by controlling minimum bending radius. Its mechanical properties are analysed based on the numerical analysis model and finite element analysis (FEM) of ø175. The sensitivity analysis of using quantity of bending restrictors is also performed to show the effect of the quantity on bending stiffness. A testing scheme of bending stiffness of the bending restrictor is then formulated based on its structure. From numerical analysis results through test simulation, the tolerance is less than 3 %, which verifies the reliability of the numerical analysis model. Performance of the bending restrictor and dynamic response are analysed according to environmental parameters that occur once per 100 years from offshore wind power farms and pipein-pipe models, respectively. The results show the bending restrictor can effectively protect cable structure, and the pipein-pipe model is suitable for calculating mechanical properties of interaction between the bending restrictor and cable.

Design and Implementation of Uni-directional GAP in Nuclear Power Plant

With the popularity and development of the Internet, network security issues become the important theme we focused on day by day, and there are some kinds of network security products, for example, firewall, intrusion detection system and so on; Uni-directional GAP, as an important protective device of network security which was used mainly in the power industry, transports uni-directional data flow absolutely from the physical and link layer. At the same time, MRP (multi redundancy technology) and other technology ensure the system's high reliability, high fault tolerance, high safety and high stability. This article begins from the current network status of the nuclear power industry, and then introduces the development, concept and operational principle of the Uni-directional GAP device, finally this article introduces the successful application of GAP which ensure the reliable, secure and efficient exchange of real-time date and history logs in the KNS system (real-time monitor system) in nuclear power plant.

모의 송전계통에 초전도한류기의 적용에 따른 거리계전기의 동작특성 연구

The development of the superconducting fault current limiter (SFCL) to apply into a power transmission system where makes larger fault current compared to the power distribution system has been performed. Among various SFCLs, the trigger-type SFCL is suitable for application into the power transmission system due to the effective reduction on power burden of the high temperature superconducting element (HTSC) for the larger fault current.<BR> To protect the power transmission line in the power grid, the distance relay, which decides to interrupt fault section where can be calculated by the measured voltage and current from sound grid, is one of important protective devices in the power transmission system. However, the operation of the distance relay from the impedance of the fault point on the transmission line is affected by the impedance of the trigger-type SFCL. Therefore, the analysis on the operational characteristics of distance relay considering the application of the SFCL is required.<BR> In this paper, the effect on the operation zones of the distance relay by the impedance of the SFCL in a power transmission system was analyzed through the PSCAD/EMTDC simulation.

Parameters Optimization of Restraint System by Analyzing the Dissipation Characteristics of Occupant Energy in Vehicle Frontal Impact

Belt and airbag are the most important protection devices in vehicle frontal crash, which can have the best protective performance when only they were well matched with vehicle body structure. In this paper the theoretical guidance for optimizing belt and airbag parameters is researched, in order to improve the effect and efficiency of parameters optimization of restraint system. Firstly, a simulation model for occupant restraint system is developed based on the finite element theory combined with multi rigid body theory, and its effectiveness for simulating the occupant dynamic response in frontal impact is validated. Then, the energy dissipation characteristics of occupant head and chest in typical frontal crash are analyzed based on the developed model. Lastly, the adaptive level of restraint system parameters are evaluated according to the dissipation characteristics of occupant energy, and theoretical guidance for parameters optimization are summarized based on the evaluation. The analysis results indicate that: (1) airbag with low stiffness cannot fully utilize the deformation of vehicle body to dissipate the energy of occupant head, but may increase the risk of head injury; (2) belt with high stiffness would apply a big force to occupant, which could increase the compression amount of chest and may increase the risk of chest injury.

Survey of High School Football Helmet Condition and Maintenance in Middle Tennessee

Approximately 1.6-3.8 million mild traumatic brain injuries occur each year as a direct result of sports participation [1-6]. Football, particularly at the high school level, is the most common sport associated with these injuries [2]. As a collision sport, helmets are an important protective device [4]. Age, condition, and fit of football helmets are important factors in optimizing their protective properties. We hypothesized that due to inconsistent staffing, a lack of resources, and decreased general awareness of the problem, high school athletic programs have suboptimal supervision and care of their helmet inventory thereby decreasing head-trauma related safety for their athletes. Further to this point, we hypothesized that helmets in private schools and suburban areas will be newer, better conditioned, and better inspected than helmets in rural and inner city areas. We undertook this study to investigate the current status of helmet testing, maintenance, and fitting in a cohort of high schools in Middle Tennessee.

Fructose prevents 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced ATP depletion and toxicity in isolated hepatocytes

The loss of viability of isolated rat hepatocytes exposed to either 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or its toxic metabolite 1-methyl-4-phenylpyridinium ion (MPP+) was prevented by addition of fructose to the incubation medium. This protection was dependent on fructose concentration, being complete at 10 mM. Addition of fructose dramatically delayed MPTP- and MPP+-induced depletion of ATP and was accompanied by a significant accumulation of lactate, indicating the occurrence of enhanced glycolytic production of ATP. Glucose was much less effective against MPTP and MPP+ toxicity, probably because it is a relatively poor substrate for glycolysis in liver cells. We conclude that depletion of ATP is a critical event in MPTP cytotoxicity in our in vitro model system, and that the use of alternative sources of ATP production may represent an important protective device against the effects of this toxic agent.

THE CUTANEOUS ABSORPTION OF MERCURY

The sound skin represents one of the important protective devices of the organism. Its morphologic structure, as well as the resistant chemical composition of the keratinous epidermal tissue, contributes to make the outer coverings of the body relatively impermeable. So far as these are albuminoid in nature they are not profoundly different from the dominant constituents of protoplasm in various organs; but the property of extreme solubility that characterizes the cutaneous keratin prevents the outer surfaces from being "washed away" by the fluids with which they so frequently come into contact or in which they sometimes become immersed. Most cellular walls or membranes in living structures tend to be permeable to some extent. It is generally regarded as established, however, that the intact skin is impermeable for watery solutions of salts or other substances. Reports of the transfer of inorganic compounds in aqueous solution into the body through the skin