Generic noise criterion curves for sensitive equipment

The design of vibration-sensitive advanced technology facilities generally involves considerable attention to structural and mechanical aspects. In most cases, the vibration control measures contribute significantly to a facility's cost. The selection of a vibration criterion for use in design is an important step in the design process. Many process equipment manufacturers have provided tool-specific criteria, and the literature contains several forms of "generic" criteria. Unfortunately, there is no standardization in either tool-specific or generic criteria, and considerable confusion can arise, often due to the forms of data representation used. This paper first reviews some of the relevant fundamentals of signal processing, then uses experimental data to develop a tool-specific vibration criterion for an optical microscope. Two dissimilar approaches to generic criteria are discussed, and their signal-processing requirements are examined. They are compared with a manufacturer's published vibration criteria for a projection aligner. Recommendations are given for future development of tool-specific criteria.

Conceptual design considerations from the acoustical design of an animal research facility are presented in this paper. Animals in laboratory settings are experimentally stressed to observe outcomes. Stressors external to the experiment confound data and reduce research productivity. Among these experimental contaminants is acoustical noise, which has well-documented extra-auditory effects in animals. Both steady-state and transient sounds can affect development, sleep, reproduction, behavior, and other parameters important to animal models. Reasonably comprehensive sensitivity data exist in the medical and laboratory literature; however, there are few treatments of the acoustical design of vivarium and animal laboratory facilities. Acoustical design of these facilities is challenging due to the broad array of sensitivities (including ultrasonic frequencies), scarcity of high-frequency data for noise sources, contamination control and cleanliness requirements, and surface durability concerns. Acoustical design criteria for animal holding areas and experimental test rooms are considered. The criteria are based not only on sound pressure levels but also on frequency content, isolation of incompatible species, expected vocalizations, and minimization of disruption. Noise sources include mechanical/electrical/plumbing equipment, maintenance activities, and other animals. The design efforts include categorization of animal groups, noise isolation concepts, acoustical design, and noise control measures.

Generic vibration and noise criteria (VC & NC) exist for semiconductor facility design purposes. This paper proposes to extend the criteria for use in nanotechnology facilities considering the higher level of sensitivity of new equipment without manufacturer's vibration criteria. Specifications are derived for air-borne and structure-borne excitation. The new criteria are referred to as 'VC-NT and NC-NT' curves and proposed to be used for the design of new laboratories and nanotechnology facilities. Three case studies are used to validate the criteria.

With the increasing number of fire incidents, efforts are being made to quantitatively evaluate the egress safety of buildings. In particular, studies that reflect the behavioural characteristics of occupants when evaluating egress safety are being conducted. However, the research on the performance design and safety evaluation of facilities where individuals vulnerable to disasters (i.e. those who have difficulty evacuating in the event of a fire) reside remains insufficient. In this study, fire evacuating simulations were performed on welfare facilities for disabled individuals with mobility issues, and the egress safety was evaluated. The fire simulations were performed using the capacity of the smoke exhaust system as a variable. Meanwhile, the variations in temperature and toxic gases according to fire duration were analyzed to calculate the available safe egress time (ASET). The egress simulations were performed using the egress delay time and the number of egress guides as variables. Then, the required safe egress time (REST) was calculated. The results show that increasing smoke exhaust system delays the attainment of tenability limits, improving ASET. Egress simulations revealed an optimal number of egress guides. Based on these findings, general criteria have been developed to assess egress safety, considering the building floor area, smoke exhaust capacity, and occupant numbers. These criteria can be applied to ensure efficient and economical safety designs for typical welfare facilities for the disabled.

Absolute risk is the probability that an individual who is free of a given disease at an initial age, a, will develop that disease in the subsequent interval (a, t]. Absolute risk is reduced by mortality from competing risks. Models of absolute risk that depend on covariates have been used to design intervention studies, to counsel patients regarding their risks of disease and to inform clinical decisions, such as whether or not to take tamoxifen to prevent breast cancer. Several general criteria have been used to evaluate models of absolute risk, including how well the model predicts the observed numbers of events in subsets of the population ("calibration"), and "discriminatory power," measured by the concordance statistic. In this paper we review some general criteria and develop specific loss function-based criteria for two applications, namely whether or not to screen a population to select subjects for further evaluation or treatment and whether or not to use a preventive intervention that has both beneficial and adverse effects. We find that high discriminatory power is much more crucial in the screening application than in the preventive intervention application. These examples indicate that the usefulness of a general criterion such as concordance depends on the application, and that using specific loss functions can lead to more appropriate assessments.

Aseptic processing and packaging has the goal of producing shelf-stable products of the highest possible quality. In order to fulfill this requirement, much attention has been paid to the process and packaging equipment. Such developments are not cheap, and require attention to the environment in which they operate, and the personnel who will operate them. Design of the facility in which the aseptic processes are carried out is important for protection of the equipment, regulatory compliance, food defense, and personnel retention and motivation. Each of the streams that feed the complex processing equipment, as well as the environmental conditions need to also comply with the highest quality standards. This chapter takes a summary look at hygienic design of facilities and equipment and peeks into different utilities that serve the aseptic processing and packaging equipment: from the landscaping, exterior walls, and entrances to the interior floor and drains, with considerations for hygienic zoning and long-term life of the building. While this chapter only manages to scratch the surface of a complete design, it aims at broadening the scope of aseptic design and giving the engineer a taste of all the details that are needed for a successful operation.

This paper presents a simple mechanical vibration and acoustic noise reduction of IF(current-frequency) starting sensorless controlled compressor. The adopted compressor is controlled by the sensorless estimation using back EMF observer in the normal speed range. In order to increase the speed up to normal sensorless speed range, the IF open-loop starting method is used. At the IF starting, the speed variation from the fluid load makes a mechanical vibration and acoustic noise. In order to reduce the mechanical vibration and acoustic noise, a simple variable torque slope with initial rotor position estimation method is proposed in this paper. The proposed method uses an initial rotor position estimation than a conventional rotor alignment method. And, the torque reference slope according to the increased open-loop speed is changed by the hysteresis error between the open-loop reference speed and the estimated speed. Because of the initial rotor position and the variable current according to the speed can reduce the collision of the compressor at standstill and low-speed region. Consequently the mechanical vibration and acoustic noise can be reduced.BRThe proposed simple variable IF starting method is verified 2.2kW IPMSM driven HVAC(Heating, Ventilation & Air conditioning) compressor. Experimental results shows the reduced vibration and acoustic noise at the starting to normal speed range.

Selection of the most appropriate method to determine the carbonate content for engineering purposes with particular regard to marls

Introduction The specific challenges in total knee arthroplasty are sufficiently well known. In order to obtain excellent long-term results, the following criteria have to be considered: ▬ General criteria: – patient selection – Correct indication – Peri-operative management ▬ Specific criteria: – Prosthetic design – Surgical technique, implantation technique – Reconstruction of the mechanical leg axis – Reconstruction of the joint line – Ligament balancing

Vibration and acoustic noise are two critical issues for switched reluctance machine (SRM). The abrupt change of phase current mainly contributes to high vibration and noise under conventional unipolar excitation, sinusoidal bipolar excitation considered in this paper can suppress the vibration in SRM. However, to realize the smooth sinusoidal bipolar excitation, different pulse-width modulation (PWM) strategies can be employed. In this paper vibration and acoustic noise of a prototype 6/4 SRM under different load and speed, which employs hysteresis current control (HCC) and space vector pulse-width modulation (SVPWM), is investigated, together with the conventional unipolar excitation, which is modulated by voltage PWM. It shows that the lowest vibration and acoustic noise are obtained if the SRM excited by the sinusoidal bipolar excitation modulated by the SVPWM, regardless the speed and load. However, the HCC technique exhibits the worst vibration and acoustic noise due to random switching frequencies and mechanical resonances, although less sensitive to the load and speed. In contrast, the acoustic noise with the conventional unipolar excitation is sensitive to both load and rotor speed, when the sinusoidal bipolar excitation modulated by SVPWM is employed it is sensitive to the speed but not to the load.

A systematic approach to identify the vibration and acoustic noise sources in a direct-torque-controlled (DTC) PM BLDC drive is presented and compared with that in BLAC DTC drive. Experimental results show that the acoustic noise may be radiated by the radial vibration of the stator and the vibration of connected mechanical parts due to torque pulsation and stator torsional vibration. In the BLDC DTC prototype drive, the interaction between the field harmonics and PWM switching current harmonics appears to be the dominant source of radial vibration and acoustic noise. If the acoustic noise in both BLDC DTC and BLAC DTC is mainly caused by the interactions between the armature reaction field harmonics themselves, and between the armature reaction field harmonics and PM field harmonics, the BLDC DTC drive is expected to produce higher acoustic noise because the phase current and hence the armature reaction field of BLDC DTC drive is rich of non-triplen odd harmonics. However, if the acoustic noise radiated from BLDC DTC and BLAC DTC drives is largely attributed to PWM switching current harmonic induced vibrations, as found in this paper, the sound pressure level in a BLDC DTC drive may be lower than its BLAC counterpart.

The dairy cattle productivity is very depending on the quality of their facilities and their environment condition. A lot of researches have been done in this area, but it is not developing the knowledge of animal dimensions and behaviours correlated with their facilities design. Complexities of dynamics zoometry is very depending on cow behaviours that it forced to use neural network (NN) approaching. Hence, the purposes of the paper is to create the concept of static and dynamic zoometry approach to guide the ergonomics facilities design and the modern of dairy cattle house based on zoometry data by using artificial neural network. The research is started with study literature of anthropometry, CAD design, dairy cattle, facility design and neural network. The next step is collecting the data of cow dimensions for static zoometry (17 variables) and cow behaviours for developing the concept of dynamics zoometry (5 variables). The static data is used as input factor and dynamic data as desire of Back Propagation NN model. The result of BPNN training is used to design the dairy cattle facilities, e.g. 3D CAD house with minimal length = 357.67 cm, minimal width = 132.03 cm (per tail) and minimal height = 205.28 cm. Finally, the paper is successfully developed the concept of zoometry approach and BPNN model as pioneer of implementing comfort knowledge.

Definitions of the species, especially those that are applicable to uniparental species, are reviewed. Characters used to distinguish species may be qualitative or quantitative: the former are possibly more useful than the latter. Among the purely sexual taxa, species determinations are likely to be based upon the genital apparatus; while in the Naididae, the genus is likely to have as a primary character the gonadal placement. At the slightly higher subfamily, or in some cases family, we strongly consider the number of segments formed in anterior regeneration.

Switched reluctance machines (SRMs) have been studied by many researchers as an alternative to the other types of electrical machines for use in electric and hybrid vehicle applications. SRMs are fault tolerant and have wide speed operating range. However, they suffer from several disadvantages, including high vibration, acoustic noise, and torque ripple. In this article, the placement of rectangular windows in both the rotor and stator poles is proposed to reduce the vibration and acoustic noise of SRMs. An iterative optimization algorithm in a wide speed range of operation using finite-element analysis (FEA) tools provides the best position and dimension of window design parameters. Multiphysics FEA is also performed to predict the vibration and acoustic noise of the optimized design. The results of this study present that placing windows in both the stator and rotor of the SRMs can significantly reduce the acoustic noise compared with the baseline SRMs. Based on the simulation results, the optimum design has been constructed as a prototype and tested in a wide speed operating condition. The simulation and experimental test validation results prove the effectiveness of the proposed design in mitigating the acoustic noise and vibration.

Due to the advantages of high efficiency, high power density, and high fault-tolerant capability, the fractional-slot concentrated-windings permanent-magnet (FSCW-PM) machines have received increased attention. [1]. However, the abundant harmonics in FSCW-PM machines will produce low-order radial electromagnetic force, thus aggravating the vibration and acoustic noise performances [2]. Therefore, many magnetomotive force (MMF) harmonic reduction techniques were proposed [3], but their abilities to reduce the low-order radial electromagnetic force were relatively poor. The purpose of this paper is to analyze the generation mechanism of low-order radial electromagnetic force from different magnetic field components, and a new design will be proposed to reduce the vibration and acoustic noise of FSCW-PM machines. New design Due to the interaction of tooth harmonics and fundamental magnetic field, the lowest order radial electromagnetic force will be generated in FSCW-PM machine, thus resulting in vibration and acoustic noise. Fig. 1 compares the stator structure of two existing and proposed machines. In the proposed unequal tooth stator, the angle of two adjacent opening-slots has been designed to control the MMF amplitude of each harmonic component. It should be noted that the fundamental wave keeps constant with the existing one, so the output performance is unchanged. However, the tooth harmonic is weakened effectively. Results In order to verify the proposed machine, the finite-element method and acoustic boundary-element method are employed to evaluate vibration and noise performances. The MMF and radial electromagnetic force between the existing and proposed machines are compared in Fig. 2 and 3, respectively. The proposed machine can effectively weaken the tooth harmonics and the radial electromagnetic force which plays a significant role in the vibration and acoustic noise of FSCW-PM machines. Fig. 4 compares the vibration spectrum between the existing and proposed machines. It can be seen that the proposed one has 12% lower vibration than the existing one. Finally, the sound power level spectrum of the proposed FSCW-PM machine is given in Fig. 5. Resonance does not occur because of the large difference between the electromagnetic force frequency and the modal frequency.