Identification Of Reliability Research Articles

Indocyanine Green (ICG) Fluorescence-Assisted Open Surgery Using the Rubina® Lens System in the Pediatric Population: A Single-Center Prospective Case Series.

There are scarce papers about the use of fluorescence-guided surgery (FGS) in the open surgical field. This study aimed to assess the usefulness of FGS in an open setting in the pediatric population and to report our preliminary experience using the Rubina® Lens system. All patients undergoing ICG fluorescence-assisted open surgery over the period September 2022-September 2023 were enrolled. Each surgical procedure was performed using the Rubina® Lens for ICG fluorescence visualization. A total of 25 patients, 14 boys and 11 girls with a median age at surgery of 5.8 years-old (range 0-15), were enrolled. Surgical indications were dermoid/epidermoid cysts of the head (n = 7), lymphangiomas of the head/neck (n = 2), thyroglossal duct cysts (n = 7), gynecomastia (n = 3), preauricular fistula (n = 2), second branchial cleft fistula (n = 1), fibrolipoma of the shoulder (n = 1) and myofibroma of the gluteal/perineal region (n = 2). In all procedures, an intralesional injection of 2.5 mg/mL ICG solution using a 30-gauge needle was administered. No adverse reactions to ICG occurred. Median operative time was 68.6 min (range 35-189). The visualization of ICG-NIRF with the Rubina® Lens was achieved in all cases. No intraoperative complications were reported. Postoperative complications occurred in 3/25 patients (12%), with gynecomastia (n = 1), thyroglossal duct cyst (n = 1) and neck lymphangioma (n = 1), who developed a fluid collection in the surgical site, requiring needle aspiration in outpatient care (Clavien-Dindo 2). Complete mass excision was confirmed with pathology reports. Based on this initial experience, FGS using the Rubina® Lens was very helpful in open surgery, providing enhanced visualization of anatomy and identification of margins, real-time reliability and low complication rate. It was easy to use, time saving, feasible and clinically safe. Previous experience in MIS is necessary to adopt this technology. The accuracy of the injection phase is important to avoid diffusion of the ICG into the perilesional tissue.

Accuracy and Interrater Reliability of Point-of-Care Ultrasonography Image Interpretation for Intussusception.

The aim of this study was to determine the accuracy and interrater reliability of (1) point-of-care ultrasound (POCUS) image interpretation for identification of intussusception and (2) reliability of secondary signs associated with intussusception among experts compared with novice POCUS reviewers. We conducted a planned secondary analysis of a prospective, convenience sample of children aged 3 months to 6 years who were evaluated with POCUS for intussusception across 17 international pediatric emergency departments between October 2018 and December 2020. A random sample of 100 POCUS examinations was reviewed by novice and expert POCUS reviewers. The primary outcome was identification of the presence or absence of intussusception. Secondary outcomes included intussusception size and the presence of trapped free fluid or echogenic foci. Accuracy was summarized using sensitivity and specificity, which were estimated via generalized mixed effects logistic regression. Interrater reliability was summarized via Light's κ statistics with bootstrapped standard errors (SEs). Accuracy and reliability of expert and novice POCUS reviewers were compared. Eighteen expert and 16 novice POCUS reviewers completed the reviews. The average expert sensitivity was 94.5% (95% confidence interval [CI], 88.6-97.5), and the specificity was 94.3% (95% CI, 90.3-96.7), significantly higher than the average novice sensitivity of 84.7% (95% CI, 74.3-91.4) and specificity of 80.4% (95% CI, 72.4, 86.7). κ was significantly greater for expert (0.679, SE 0.039) compared with novice POCUS reviewers (0.424, SE 0.044; difference 0.256, SE 0.033). For our secondary outcome measure of intussusception size, κ was significantly greater for experts (0.661, SE 0.038) compared with novices (0.397, SE 0.041; difference 0.264, SE 0.029). Interrater reliability was weak for expert and minimal for novice reviewers regarding the detection of trapped free fluid and echogenic foci. Expert POCUS reviewers demonstrate high accuracy and moderate interrater reliability when identifying intussusception via image interpretation and perform better than novice reviewers.

Status and Gap in Rechargeable Lithium Battery Supply Chain: Importance of Quantitative Failure Analysis

Rechargeable lithium batteries (RLBs), including lithium-ion batteries (LIBs), are accelerating the electrification of transportation and grid energy storage. This transformation of the transportation and energy sector could bring more clean energy into our energy security. The RLB technology is growing rapidly in these sectors due to substantial cost reductions and mobility needs. Yet, the durability, reliability, and safety issues of RLB remain concerns due to the nature of high-energy content in RLB. The concern of limited resources of the critical materials to sustain the RLB use is also escalated. Reuse and recycling of RLB to extend the useful life and recovery of the critical materials become important. Here, we provide a critical review of these topics to give a timely assessment of the status and gap of the RLB technologies and their supply chain. A key concept to use a quantitative failure mode and effect analysis is proposed to help advance RLB design, development, manufacturing, and deployment. The approach can be a viable method to enable physical principle-based technology assessment, failure identification, quantification, and verification of reliability and safety issues in the RLB supply chain.

Automatic Recognition Algorithm of Information Architecture Reliability Based on Energy Internet Network Topology

As a type of energy network, the scale of the power network is constantly expanding, and its structure has become more and more complicated. Correspondingly, the risks to the energy network are even less likely to be discovered, which will undoubtedly cause great troubles for the safe operation of the network. The traditional manual inspection method can no longer meet the requirements of huge and complex energy networks. Therefore, this paper proposes the algorithm, a research on the automatic identification of reliability of information architecture based on the topology of the energy Internet network. Abstract the server, storage, and other devices in the Energy Internet as network nodes, divide them according to service modules, and use Bayes estimation to evaluate and judge the impact of these nodes on the system function, so as to find the nodes with hidden risks. The results show that, compared with the traditional manual inspection method, the method proposed in this paper can efficiently and accurately find the nodes with risks and can help optimize the topology of the energy Internet network.

Identification of Web Site Reliability through Data Scrapping at Web Crawler’s Navigation

Searching a specified content on the web site is like epistle a single character in bunch of pages. When the user enters their keyword into any search engines, it takes that in to web server mining process for collecting the entire terms related to that entered key phrase. Few pages gives legal and authenticated matter for the user, which they really wanted to access. Whereas many other pages are bringing them some unwanted and malicious codes of pages or virus activity pages to harm user’s activities and the system’s functions. Generally a web page attacks the targeted system by faulty instructions and malevolent programs through some sort of intrusion methodologies are called as phishing. In this attacking method user is set to access unknown or illegal sites by the way of accessing some unidentified websites link imbedding with legal site contents. Once victim’s system performance got compromised then hackers started to do attack. To avoid this kind of molestations, user needs to understand reliability of web page’s contents before started to continue browsing. This research paper is going to present web crawler architecture, design complexities and implementation for scrapping web contents from visited web pages for indentifying their reliability and freshness.

Ideal position and size selection of unified power flow controllers (UPFCs) to upgrade the dynamic stability of systems: An antlion optimiser and invasive weed optimisation Algorithm

This paper proposes a hybrid methodology to improve the dynamic strength of frameworks by optimally locating and sizing the unified power flow controller (UPFC). The proposed method combines both the antlion optimiser (ALO) and invasive weed optimisation (IWO) techniques. The advantages of the proposed methodology are enhanced searching ability, better identification of optimal solutions and greater reliability. Initially, to locate UPFCs, using the ALO technique, the most extreme power loss bus is recognised as the optimal location. The capacity required to resolve the situation is determined by the IWO technique based on the minimum power loss, voltage deviation and establishment cost of the UPFCs. The proposed system is actualised and aims at the matrix laboratory (MATLAB) environment, while the power flow security and voltage stability are evaluated on the basis of the Institute of Electrical and Electronics Engineers (IEEE) standard benchmark system. At this point, voltage stability, power loss, overloading and UPFC costs are analysed through changing the system load and generation. The proposed working method is then assessed and compared with traditional techniques.

Biomechanical analysis of the interaction phenomena between artificial urinary sphincter and urethral duct.

Male urinary incontinence is a widespread healthcare problem, leading to a miserable quality of life. Artificial urinary sphincter (AUS) is a device inserted mostly around the urethra in adult males, which mimics the urinary sphincter by providing a closure during urinary storage and a subsequent open to permit voiding. The interaction phenomena occurring between AUS cuff and urethral duct represent a fundamental problem in the investigation of AUS reliability and durability. In this work, computational methods are exploited to deeply investigate the mechanics of interaction phenomena occurring between urethral duct and AUS device. Experimental studies are performed on urethral tissues, and structural tests are carried out on the overall urethral duct to obtain a large set of information required for mechanical properties definition. The mechanical behavior of AUS cuff is investigated using mechanical and physicochemical procedures. The cuff conformation is acquired by computed tomography techniques for the definition of the numerical model. Numerical analyses are developed to evaluate the mechanical response of urethral duct in interaction with AUS cuff, considering the lumen occlusion process for maintaining urinary continence. Finally, the investigation of the compressive stress and strain fields within urethral tissues allows the identification of device performance and reliability in correlation with surgical practice.

Development of a Data-driven Model for Marine Gas Turbine (MGT) Engine Health Monitoring

Throughout the United States Navy, marine gas turbines (MGT) are used for the production of propulsive and electric power aboard many surface ships. The operational availability of these ships during deployments is contingent on the health and reliability of the installed MGTs. Currently, to ensure the health and proper functionality of these turbines, a series of manual evaluations are employed with varying success (e.g., pre-deployment visual inspections, periodic inspections of predefined wear out modes, characteristic vibration surveys, Integrated Performance Analysis Reports). This paper examines historical records associated with the General Electric LM2500 MGT installed for propulsion aboard Guided Missile Destroyers (DDG) and Guided Missile Cruisers (CG) to develop a deployable model of a healthy engine for the automated, near-real time comparison of sensed data. In traditional gas-path analysis (GPA), parameters such as compressor discharge pressure (CDP), compressor inlet temperature (CIT), and exhaust gas temperature (EGT) are predicted as a function of engine speed using baseline engine data and correction factors. Implementation of GPA in the MGT environment is particularly challenging, as analysis will be limited to narrow operation bands and not account for influence factors such as engine load or the performance of critical subsystems on the engine. In this work, a multi-layer perceptron (MLP) regression model is developed in order to capture the nonlinear relationships between engine controller inputs, external loads, and ambient conditions to selected sensor outputs such as gas generator speed (NGG), low pressure turbine speed (NPT ), and power turbine inlet pressure (P54). Optimal inputs and outputs are chosen using both mutual information (MI) scores and input from subject matter experts. A healthy data set was created using data from 60 MGT’s in service and time-synchronized failure records over a five year period from 2012 to 2017. An inter-engine model was trained from the healthy data set and used to generate model residuals, which show strong correlation with a variety of critical failure modes reported in maintenance history, thus enabling automatic fault detection and remote identification of asset health and reliability.

Environmental risk assessment of biocidal products: identification of relevant components and reliability of a component-based mixture assessment

BackgroundBiocidal products are mixtures of one or more active substances (a.s.) and a broad range of formulation additives. There is regulatory guidance currently under development that will specify how the combined effects of the a.s. and any relevant formulation additives shall be considered in the environmental risk assessment of biocidal products. The default option is a component-based approach (CBA) by which the toxicity of the product is predicted from the toxicity of ‘relevant’ components using concentration addition. Hence, unequivocal and practicable criteria are required for identifying the ‘relevant’ components to ensure protectiveness of the CBA, while avoiding unnecessary workload resulting from including by default components that do not significantly contribute to the product toxicity. The present study evaluated a set of different criteria for identifying ‘relevant’ components using confidential information on the composition of 21 wood preservative products. Theoretical approaches were complemented by experimentally testing the aquatic toxicity of seven selected products.ResultsFor three of the seven tested products, the toxicity was underestimated for the most sensitive endpoint (green algae) by more than factor 2 if only the a.s. were considered in the CBA. This illustrated the necessity of including at least some additives along with the a.s. Considering additives that were deemed ‘relevant’ by the tentatively established criteria reduced the underestimation of toxicity for two of the three products. A lack of data for one specific additive was identified as the most likely reason for the remaining toxicity underestimation of the third product. In three other products, toxicity was overestimated by more than factor 2, while prediction and observation fitted well for the seventh product. Considering all additives in the prediction increased only the degree of overestimation.ConclusionsSupported by theoretical calculations and experimental verifications, the present study developed criteria for the identification of CBA-relevant components in a biocidal product. These criteria are based on existing criteria stated in the regulation for classification, labelling and packaging of substances. The CBA was found sufficiently protective and reliable for the tested products when applying the here recommended criteria. The lack of available aquatic toxicity data for some of the identified relevant components was the main reason for underestimation of product toxicity.

Kinematically Admissible Failure Mechanisms for Plane Trusses

The reliability models of statically indeterminate steel trusses are analysed in this paper. The plane trusses are considered. For analysed structures types of reliability model are determined. Identification of system reliability is based on studies on the transformation from the safe structural system into the geometrically variable system (mechanism). These researches intended to determine the kinematically admissible failure mechanisms which contain minimal critical sets of elements. For analysed truss the formula setting out the number of mechanisms for any number of repeatable sections is determined. To identify the mechanism, spectral analysis of the linear stiffness matrix is used. This stage of the study, in conjunction with consideration of static loads, allows to determine the minimum critical set of rods corresponding to the most probable scenario of the structural damage. For these analysis the computer program based on the finite element method has been created within the Mathematica environment.

Identification of Operator Reliability on Sewing Department According to Task Analysis

PT. XYZ is one of the textile companies that produces garments exported to some countries . The company has identified Sewing Department has an error rate above the target at around 1.5%. Similar models were worked Line A1 and A7 has a productivity rate is only 77.14% (below the company's target percentage of 80% ) . This study aimed to identify reliability sewing operator so it can be used as a basis for identifying an increase in productivity of the operator at the Department of Sewing at PT. XYZ . This research method using human reliability (Human Reliability Assessment) is based on the task analysis that method Technique for Human Error Rate Prediction (THERP), Method of Human Error Assessment and Reduction Technique (HEART) and the method of Standardized Plant Analysis Risk Human Reliability Assessment (SPAR-H) to measure the reliability of the operator in the task. Fault Tree Analysis (FTA) is used as a technique to analyze the causal relationship of a risk assessment and measurement reliability. Rework type on Line A1 there are 6 tasks and Line A7 there are 5 task . From analysis to Human Error Probability (HEP) on Fault Tree turns HEART method has the highest value compared to SPAR-H and THERP methods. HEP analysis using HEART method s on Line A1 of 0.319 while the Line A7 of 0.399. Potential reworks using SPAR-H Method on Line A1 and A7 is the task 4 with a HEP value on Line A1 of 0.00959 and Line A7 of 0.00209 . HEP analysis using THERP Method for Line A1 of 0.1615 while the Line of 0.2001. Sewing operator reliability in identifying an increase in labor productivity on Line A1 and A7 looks at HEP value for each task performed. On Line A1 and A7 seen that the HEP is below 0.5 means the reliability of operators in doing the task can be improved with the cooperation of all the company components .

Predicting Stability of Mild Cognitive Impairment (MCI): Findings of a Community Based Sample.

Mild Cognitive Impairment (MCI) is a risk factor for Alzheimer's disease (AD) and other forms of dementia. However, much heterogeneity concerning neuropsychological measures, prevalence and progression rates impedes distinct diagnosis and treatment implications. Aim of the present study was the identification of specific tests providing a high certainty for stable MCI and factors that precipitate instability of MCI in a community based sample examined at three measurement points. 130 participants were tested annually with an extensive test battery including measures of memory, language, executive functions, intelligence and dementia screening tests. Exclusion criteria at baseline comprised, severe cognitive deficits (e.g. diagnosis of dementia, psychiatric or neurological disease). Possible predictors for stability or instability of MCI-diagnosis were analyzed using Regression and Receiver Operating Characteristic (ROC) curve analysis. Age, IQ and APOE status were tested for moderating effects on the interaction of test performances and group membership. A high prevalence of MCI (49%) was observed at baseline with a reversion rate of 18% after two years. Stability of MCI was related to performances in four measures (VLMT: delayed recall, CERAD: recall drawings, CERAD: Boston Naming Test, Benton Visual Retention Test: number of mistakes). Conversion to MCI is associated with language functions. Reversion to 'normal' was primarily predicted by single domain impairment. There was no significant influence of demographic, medical or genetic variables. The results highlight the role of repeated measurements for a reliable identification of functional neuropsychological predictors and better diagnostic reliability. In cases of high uncertainty close monitoring over time is needed in order of estimating outcome.

Implementing the Habitats Directive: How science can support decision making

The overall goal of the Habitats Directive is to maintain or restore natural habitats and species in a favourable conservation status. An important role in the implementation process is assigned to science. For three core elements, defining the favourable conservation status, development of best practice measures, and monitoring of the conservation status, we outline how science can support decision making. To do so, we use experiences from the ongoing process in Flanders (northern Belgium). First, when determining the favourable conservation status, information on reference values are embedded in a specifically developed calibration model where thresholds on range, area, and quality are set for habitats. Subsequently, socio-economical requirements are taken into consideration, without compromising the favourable conservation status. When it comes to conducting measures, science adds to the knowledge on developing and optimizing cost-effective conservation and restoration management measures. Finally, monitoring of the conservation status will be based on the principle of statistically sound methodologies, enabling the identification of reliability in the assessments made. For habitats, information on area will be gathered through a surface-covering mapping, while quality will be assessed via a sample-oriented monitoring scheme. For species, maximal collaboration with non-governmental organisations will be undertaken, with scientific support on data recording and processing. Overall, the obtained insights will help policy makers to define the framework and set priorities, take the appropriate measures, and keep a finger on the pulse through monitoring data.

Reliability Verification of STEAM Program Evaluation System and Feasibility by Correlation Analysis

The cultivation of convergence human resources for the complicated and diversified future society shall be conducted based on the intrinsic understanding and recognition of STEAM by evaluating and applying the education activity systematically and seeking the direction of new education. This study intended to draw the importance and priority of evaluation contents through questionnaire for the weighted value objectified based on composition of evaluation items and standard indication necessary for DOT LAB program as a part of securing the rationality of education evaluation for STEAM program. Based on the analysis result of this questionnaire, this study aims to analyze and diagnose the correlation with quantitative approach for identification and verification of reliability and correlation for the weighted value and realize the objective rationality. In the previous study, among 4 kinds of evaluation areas, the importance and priority was distributed in the order of ‘concept recognition’>‘content composition’=‘convergence application’>‘creativity’. In concrete, it is composed of total 100 points including 30 points for ‘concept recognition’, 25 points for ‘convergence application’ and ‘contents composition’, respectively and finally 20 points for ‘creativity’. Thus, the evaluation of ‘DOT LAB program’ was carried out by allocating the rating in factors that the index of each item has which is evaluated more importantly instead of allocating the same score to all items as we judged the necessity of segmented and differential evaluation, and the correlation between factors was identified to realize the reliability.

Analysis of Visual Sensibility Evaluation of Naturally Colored Organic Cotton: Identification of Reliability and Proper Scouring Method

Objective: The present study was intended to identify (1) the intra- and inter-rater reliabilities of a visual sensibility evaluation protocol and (2) the effects of NaCOC color and scouring method on the visual sensibility of NaCOC. Thirty female participants(20s & 30s) were participated in the visual sensibility evaluation of NaCOC. Background: Interests in naturally colored organic cotton(NaCOC) increase rapidly in parallel with the social trend of eco-friendly living and wellbeing. Method: Three color sets (ivory, green, and coyote-brown) of NaCOC specimens including one untreated and four treated specimens(Na₂CO₃; NaOH; enzyme; boiling water) were examined in the study. The visual sensibility evaluation was conducted by the test-retest method using nine pairs of bipolar visual sensibility adjectives(bright-dark; clear-murky; heavy-light; vivid-subdued; warm-cool; fresh-stale; strong-weak; showy-plain; and luxurious-cheap). Results: As a result of reliability of a visual sensibility evaluation protocol, inter-rater variability(average SD=1.06) of visual sensibility evaluation was more than 1.4 times the intra-rater variability(average SD=0.74). However, both the sensibility evaluation reliabilities did not show any systematic pattern of changes. Lastly, ANOVA and post-hoc analysis showed that preferred scouring methods for a visual sensibility adjective pair significantly vary depending on NaCOC color. Application: Both the reliability of visual sensibility evaluation protocol and the analysis of proper scoring method of NaCOC in the study would be useful information to design the affective textile.

Reliability and Safety of Complex Technical Systems an Overall Approach

Reliability and Safety of Complex Technical Systems an Overall ApproachThe paper is concerned with the identification, evaluation, prediction and optimization of reliability, availability and safety of technical systems related to their operation processes. The main emphasis is on multi-state systems composed of ageing components and changing during their operation their structures and their components reliability and safety characteristics. The convenient tools suggested for analyzing these complex technical systems are semi-markov modeling of the systems' operation processes and multistate approach to the systems' reliability modeling. The paper describes current theoretical results on the proposed approach to reliability and safety analysis of multi-state systems with ageing components in their operation processes and the possibility of their practical applications to the reliability, safety analysis and optimization of the complex technical port and maritime transportation systems.

Building model analysis applications with the Joint Universal Parameter IdenTification and Evaluation of Reliability (JUPITER) API

The open-source, public domain JUPITER ( Joint Universal Parameter Iden Tification and Evaluation of Reliability) API ( Application Programming Interface) provides conventions and Fortran-90 modules to develop applications (computer programs) for analyzing process models. The input and output conventions allow application users to access various applications and the analysis methods they embody with a minimum of time and effort. Process models simulate, for example, physical, chemical, and (or) biological systems of interest using phenomenological, theoretical, or heuristic approaches. The types of model analyses supported by the JUPITER API include, but are not limited to, sensitivity analysis, data needs assessment, calibration, uncertainty analysis, model discrimination, and optimization. The advantages provided by the JUPITER API for users and programmers allow for rapid programming and testing of new ideas. Application-specific coding can be in languages other than the Fortran-90 of the API. This article briefly describes the capabilities and utility of the JUPITER API, lists existing applications, and uses UCODE_2005 as an example.

Attention-Deficit/Hyperactivity Disorder: APA Research Challenges

The purpose of this paper is to present a critical analysis of the research methods in adapted physical activity studies about children with attention-deficit hyperactivity disorder (ADHD). The strengths and weaknesses of various research methods are discussed by (a) three main types of research questions, (b) identification and description of research participants, (c) reliability and validity of assessment instruments, (d) data collection procedures, and (e) quantitative and qualitative methods of data analysis. Strategies to improve research are embedded in each of the five main categories. It is concluded that substantial methodological inconsistencies exist in the current ADHD physical activity literature base. Future research would be strengthened by incorporating recommended suggestions.

Comparison of methods for the identification of coagulase-negative staphylococci

Coagulase-negative staphylococci (CNS) species identification is still difficult for most clinical laboratories. The scheme proposed by Kloos and Schleifer and modified by Bannerman is the reference method used for the identification of staphylococcal species and subspecies; however, this method is relatively laborious for routine use since it requires the utilization of a large number of biochemical tests. The objective of the present study was to compare four methods, i.e., the reference method, the API Staph system (bioMérieux) and two methods modified from the reference method in our laboratory (simplified method and disk method), in the identification of 100 CNS strains. Compared to the reference method, the simplified method and disk method correctly identified 100 and 99% of the CNS species, respectively, while this rate was 84% for the API Staph system. Inaccurate identification by the API Staph method was observed for Staphylococcus epidermidis (2.2%), S. hominis (25%), S. haemolyticus (37.5%), and S. warneri (47.1%). The simplified method using the simple identification scheme proposed in the present study was found to be efficient for all strains tested, with 100% sensitivity and specificity and proved to be available alternative for the identification of staphylococci, offering, higher reliability and lower cost than the currently available commercial systems. This method would be very useful in clinical microbiology laboratory, especially in places with limited resources.

Development of Vacuum Insulation Technology for a Multifunctional Vacuum Interrupter Loaded into an SF6 Gas Free 24 kV Switchgear

We developed a multifunctional vacuum interrupter that has three functions: current interruption, disconnection, and earth operation in a vacuum vessel. Using the multifunctional vacuum interrupter, we realized 24 kV, 630 A, 25 kA rated switchgear that do not use SF6 gas. In addition, we could downsize the switchgear greatly compared with conventional switchgear by applying excellent vacuum insulation characteristics. In this paper, we report the backgrounds and the solutions of the following technical problems regarding vacuum insulation inside the multifunctional vacuum interrupter: (1) Improvement of breakdown voltage between the vacuum vessel and high voltage flexible conductors, (2) optimization on the shape of shielding electrodes set at both ends of an insulating rod, (3) removal of conductive micro particles and improvement of breakdown voltage between contacts by using AC working voltage, and (4) identification of long-term reliability of vacuum insulation under the continuous application of AC working voltage.