One-shot System Research Articles

A Study on the Proper Inspection Cycle Plan Through Reliability Analysis of One-Shot System

A Study on the Proper Inspection Cycle Plan Through Reliability Analysis of One-Shot System

MICROSTRUCTURAL CHARACTERISATION, RHEOLOGICAL AND WATER ABSORPTION PROPERTIES OF FILLED POLYURETHANE FOAM

This work investigates the microstructural characterization, rheological and water absorption properties of granite and feldspar filled polyurethane foam. Foaming of polyurethane with the use of synthetic materilas as suitable additives remain a major setback for polyurethane foams. Hence, granite and feldspar are selected as the fillers, pulverized and sieved to ˂90 µm and are randomly dispersed into the polyurethane matrix. The matrix constituents were mixed in the same ratio while fillers were introduced via a one-shot system approach in predetermined proportions of 3-7 wt%. The work was carried out to identify optimum fillers to be utilized in the production of rigid polyurethane foams given the effect of the fillers on the microstructural characterisation, rheological and water absorption properties of the foams. SEM, XRF and FTIR analysis were used characterize the foams while rheological and water absorption tests are also carried out. The presence of the fillers in the foam showed a rupture in the structure of the foams with the cells having similar arrangements. The cream, gel, rise, and the tack-free time was delayed with the presence of the filler particles. It was discovered that 7 wt% feldspar addition enhances the cream and gel time while 3 wt% granite enhance rise and tack free time, respectively in the optima conditions. It was discovered that the two fillers had inverse effects on the rheological properties. The addition of granite and feldspar degrades the sulfonic acid groups and promoted the appearance of Si-O stretching vibration band

A Study on How to Extend The Inspection Period for The One-Shot System

A Study on How to Extend The Inspection Period for The One-Shot System

Comparative investigation of the influence of kaolin and dolomite on the properties of polyurethane foam

This work investigates the influence of kaolin and dolomite on the properties of polyurethane foam. The selected fillers were pulverized and sieved to obtained < 90 μm that were used as reinforcements in the polyurethane matrix in a randomly dispersed mode. The matrix constituents were mixed in the same ratio while fillers were introduced via a one-shot system approach in predetermined proportions of 3–7 wt.%. The work was carried out to identify optimum fillers to be utilized in the production of polyurethane rigid foams given the effect of the fillers on the physical, mechanical, and chemical properties of the foam. FTIR, XRF, and SEM and mechanical property tests were carried out on the filled polyurethane foam. The presence of the fillers in the foam showed a rupture in the structure of the foams with the cells having similar arrangements. The addition of dolomite and Kaolin degrades the sulfonic acid groups and promoted the appearance of Si–O stretching vibration band. The density, hardness, flexural and compressive strengths of the polyurethane foam were enhanced with the the addition of dolomite and kaolin particles.

Reliability and Remaining Life Assessment of an Electronic Fuze Using Accelerated Life Testing

An electronic fuze is a one-shot system that has a long storage life and high mission criticality. Fuzes are designed, developed, and tested for high reliability (over 99%) with a confidence level of more than 95%. The electronic circuit of a fuze is embedded in the fuze assembly, and thus is not visible. Go/NoGo fuze assembly mission critical testing does not provide prognostic information about electrical and electronic circuits and subtle causes of failure. Longer storage times and harsh conditions cause degradation at the component level. In order to calculate accrued damage due to storage and operational stresses, it is necessary to perform sample-based accelerated life testing after a certain time and estimate the remaining useful life of mission critical parts. Reliability studies of mechanical parts of such systems using nondestructive testing (NDT) have been performed, but a thorough investigation is missing with regards to the electronic parts. The objective of this study is to identify weak links and estimate the reliability and remaining useful life of electronic and detonating parts. Three critical components are identified in an electronic fuze circuit (1) a diode, (2) a capacitor, and (3) a squib or detonator. The accelerated test results reveal that after ten years of storage life, there is no significant degradation in active components while passive components need to be replaced. The squib has a remaining useful life (RUL) of more than ten years with reliability over 99%.

System Reliability Estimation of Divert Attitude Control System of a Launch Vehicle using Bayesian Networks

Divert attitude and control system (DACS) is a one-shot system and provides attitude correction and translation of the Launch vehicle. DACS consists of many flight critical sub systems which are arranged in a series configuration. The traditional Reliability block diagram and Fault tree diagram methods are unsuitable for reliability modelling, when considering uncertainty among the components and system. Bayesian network is the natural choice to model dependencies among the components and system. DACS being one shot system, it is very expensive and time consuming to test more number of systems during the design and development. Hence the data is drawn from component level, subsystem level and expert opinion is used for reliability estimation. In this paper, Bayesian network modelling of DAC system was carried out for estimating the reliability using multi-level data. An algorithm is developed for computation of Conditional probabilities in Bayesian network. Posterior probability distribution of components is calculated using Markov Chain Monte Carlo (MCMC) simulations and results are compared with Junction tree based exact inference algorithm. MATLAB code is developed to estimate the reliability of DAC system.

원샷시스템의 신뢰도 척도 설정 방안

원샷시스템의 신뢰도 척도 설정 방안

From Neurorobotic Localization to Autonomous Vehicles

The navigation of autonomous vehicles is confronted to the problem of an efficient place recognition system which is able to handle outdoor environments on the long run. The current Simultaneous Localization and Mapping (SLAM) and place recognition solutions have limitations that prevent them from achieving the performances needed for autonomous driving. This paper suggests handling the problem from another perspective by taking inspiration from biological models. We propose a neural architecture for the localization of an autonomous vehicle based on a neurorobotic model of the place cells (PC) found in the hippocampus of mammals. This model is based on an attentional mechanism and only takes into account visual information from a mono-camera and the orientation information to self-localize. It has the advantage to work with low resolution camera without the need of calibration. It also does not need a long learning phase as it uses a one-shot learning system. Such a localization model has already been integrated in a robot control architecture which allows for successful navigation both in indoor and small outdoor environments. The contribution of this paper is to study how it passes the scale change by evaluating the performance of this model over much larger outdoor environments. Eight experiments using real data (image and orientation) grabbed by a moving vehicle are studied (coming from the KITTI odometry datasets and datasets taken with VEDECOM vehicles). Results show the strong adaptability to different kinds of environments of this bio-inspired model primarily developed for indoor navigation.

A Method of Failure Detection Rate Calculation for Setting up of Guided Missile Periodic Test and Application Case

Since guided missiles with the characteristics of the one-shot system remain stored throughout their entire life cycle, it is important to maintain their storage reliability until the launch. As part of maintaining storage reliability, period of preventive test is set up to perform preventive periodic test, in this case failure detection rate has a great effect on setting up period of preventive test to maintain storage reliability. The proposed method utilizes failure rate predicted by the software on the basis of MIL-HDBK-217F and failure mode analyzed through FMEA (Failure Mode and Effect Analysis) using data generated from the actual field. The failure detection rate of using the proposed method is applied to set periodic test of the actual guided missile. The proposed method in this paper has advantages in accuracy and objectivity because it utilizes a large amount of data generated in the actual field.

Storage availability of one-shot system under periodic inspection considering inspection error

This paper presents a model to find the optimal inspection intervals for one-shot system with n components under periodic inspection. We assume that the failure times of all components in a series structure are independent and follow an exponential distribution. In this model, the inspection is imperfect, and there can be undiscovered failures. The undiscovered failures can be detected at the following inspection time points. The interval availability and life cycle cost are considered as optimization criteria are derived analytically. A simulation algorithm procedure is also developed with Monte Carlo simulation to obtain the optimal inspection intervals. In illustration examples, we first calculate the system availability under periodic inspection through the analytical model and investigate the effect of inspection error on the storage availability. We then study the impacts of inspection and cost parameters on the optimal inspection intervals through a sensitivity analysis.

Replacement timing for a one-shot system with minimal repair

Replacement timing for a one-shot system with minimal repair

Semifluorinated Synergistic Nonfouling/Fouling-Release Surface.

The preparation of a fluorine-containing synergistic nonfouling/fouling-release surface, using a b-PFMA-PEO asymmetric molecular brush possessing both poly(ethylene glycol) (PEO) and poly(2,2,2-trifluoroethyl methacrylate) (PFMA) side chains densely distributed on the same repeat unit along the polymeric backbone, is reported. On the basis of the poly(Br-acrylate-alkyne) macroagent comprising two functionalities (alkynyl and 2-bromopropionate), which is prepared by reversible addition-fragmentation chain transfer homopolymerization of a new trifunctional acrylate monomer of Br-acrylate-alkyne, b-PFMA-PEO asymmetric molecular brushes are obtained by concurrent atom transfer radical polymerization and Cu-catalyzed azide/alkyne cycloaddition "click" reaction in a one-shot system. A spin-cast thin film of the b-PFMA-PEO asymmetric molecular brush exhibits a synergistic antifouling property, in which PEO side chains endow the surface with a nonfouling characteristic, whereas PFMA side chains display the fouling-release functionality because of their low surface energy. Both protein adsorption and cell adhesion tests provided estimates of the antifouling activity of the asymmetric molecular brush surfaces, which was demonstrated to be influenced by the degree of polymerization of the backbone and the length of the PEO and PFMA side chains. With compositional heterogeneities, all asymmetric molecular brush surfaces show considerable antifouling performance with much less protein adsorption (at least 45% off, up to 75% off) and cell adhesion (at least 70% off, up to 90% off) in comparison with a bare surface.

Redo renal denervation using amulti-electrode radiofrequency system in patients with persistent therapy-resistant hypertension.

ObjectivesRenal sympathetic denervation has been studied as a potential therapeutic option for patients with therapy-resistant hypertension; however, a significant proportion of patients do not show a significant reduction in blood pressure and are classified as non-responders. The objective of the present study was to assess whether a redo renal denervation procedure increases response rates.MethodsWe present a case series of three consecutive renal denervation non-responders treated with the multi-electrode radiofrequency St. Jude EnligHTN catheter after an average of 22 months. Patients were followed for 6 months.ResultsMean age was 66 years and two patients were male. Patients were previously treated using either ReCor’s Paradise system, the Vessix V2 system or the Covidien OneShot system. Mean office blood pressure one year after the initial procedure was 187/102 mm Hg with a mean 24 h ambulatory blood pressure of 166/102 mm Hg. All patients underwent a successful redo procedure using the EnligHTN system because of persistent therapy-resistant hypertension. At 6 months a significant drop in both office and ambulatory blood pressure of −27/−6 mm Hg and −15/−13 mm Hg, respectively, was observed. No significant renal artery stenosis was observed at 6 months.ConclusionsIn patients with therapy-resistant hypertension who do not respond to an initial renal denervation procedure, a redo procedure using the St. Jude EnligHTN system may help to significantly improve blood pressure control.

Reliability Analysis and Redundancy Allocation for a One-Shot System Containing Multifunctional Components

Enabling more than one function in a component provides a new cost-effective way to develop a highly reliable system. In this paper, we study the reliability of a one-shot system containing multifunctional components. Such systems have attracted increasing attention in many areas, such as ad hoc sensor networks. We derive the expressions for system reliability and reliability of each function, and formulate a redundancy allocation problem (RAP) with the objective of maximizing system reliability. Unlike constructing a system with single-functional components, the number of copies of a specific function to be included in each multifunctional component (i.e., functional redundancy) needs to be determined as part of the design. Moreover, a start-up strategy for turning on specific functions in these components must be decided prior to system operation. We develop a heuristic algorithm and include it in a two-stage genetic algorithm (GA) to solve the new RAP. We also apply a Tabu search (TS) method for solving such NP-hard problems. Our numerical studies illustrate that the two-stage GA and the TS method are quite effective in searching for high-quality solutions.

Periodic and Non-Periodic Inspection Policies for a One-Shot System with Minimal Repair

Periodic and Non-Periodic Inspection Policies for a One-Shot System with Minimal Repair

서비스디자인에서 더블다이아몬드 모델에 의한 기업의 CSV활동 사례

Currently, the enterprises are introducing the concept of shared value creation called the CSV(Creating Shared Value) by integrating the intrinsic value creating activities and social contributions. Enterprises as a strategy for pursuing the sustainable of CSV not the oneshot system can develop the human relations through the service design areas which are being accessed. This study has attempted to propose the strategic implications for the vitalization of service design and the spread of CSV by introducing the double diamond model of the British Council to analyze how it was applied in the phase of discovery, defining, developing and delivery and also by collecting four examples of enterprises which have introduced the service design in the CSV activities. Implications include, first, the service design application for the CSV strategy is effective for sustainable business management even though it's not a directly profit, Second, when the enterprises promote the service design, they have to realize that the phase of accurately discovering the social problems must be prioritized. And the identify on the direction of service design must be established so that the model can be sustainable. an effective way for providing feedback, assessing results and establishing the strategies for the service with authenticity is required since a direct and indirect participation of consumers are made. Third, when introducing the methodologies of the service design, a consideration must be given so that the core value of CSV is not dispersed. Through this study, I hope positive results can be obtained for the enterprises based on the CSV by actively applying the service design in the management strategies of the future market so that economic and social benefits can be pursued in the business opportunities of enterprises.

Optimal Maintenance Policy of a Multi-Unit One-Shot System with Minimal Repair

A one-shot system is a system that can be used only once during its life, and whose failures are detected only through inspections. In this paper, we discuss an inspection policy problem of one-shot system composed of multi-unit in series. Failed units are minimally repaired when failures are detected and all units in the system are replaced when the nth failure is detected after the last replacement. We derive the expected cost rate approximately. Our goal is to determine the optimal inspection policy that minimizes the expected cost rate.

Optimum Maintenance Policy for a One-Shot System with Series Structure Considering Minimal Repair

One-shot systems such as missiles and extinguishers are placed in storage for a long time and used only once during their lives. Their reliability deteriorates with time even when they are in storage, and their failures are detected only through inspections for their characteristics. Thus, we need to decide an appropriate inspection policy for such systems. In this paper, we deal with a system comprising non-identical units in series, where only minimal repairs are performed when unit failures are detected by periodic inspections. The system is replaced and becomes “as good as new” when the nth failure of the system is detected. Our objective is to find the optimal inspection interval and number of failures before replacement that minimize the expected total system cost per unit of time.

Metaheuristic-based inspection policy for a one-shot system with two types of units

In this paper, we address an inspection policy problem for a one-shot system with two types of units, namely, Type 1 units that fail at random times and Type 2 units that degrade with time. Interval availability and life cycle cost are used as optimization criteria and estimated by simulation. We determine inspection intervals, preventive replacement ages of Type 1 units, and preventive maintenance thresholds of Type 2 units that have minimal life cycle cost and satisfy the target interval availability during inspection periods. A simulation-based optimization procedure using a hybrid genetic algorithm is proposed to find near-optimal solutions. Numerical examples are studied to investigate the effects of model parameters on optimal solutions and compare the hybrid genetic algorithm with the general genetic algorithm.

Simulation-Based Inspection Policies for a One-Shot System in Storage Over a Finite Time Span

In this paper, we consider an inspection policy problem for a one-shot system with two types of units over a finite time span and want to determine inspection intervals optimally with given replacement points of Type 2 units. The interval availability and life cycle cost are used as optimization criteria and estimated by simulation. Two optimization models are proposed to find the optimal inspection intervals for the exponential and general distributions. A heuristic method and a genetic algorithm are proposed to find the near-optimal inspection intervals, to satisfy the target interval availability and minimize the life-cycle cost. We study numerical examples to compare the heuristic method with the genetic algorithm and investigate the effect of model parameters to the optimal solutions.