Gauge Accuracy Research Articles

Localization of hidden leaks in water supply networks by hydraulic methods

AbstractThe hydraulic gradient method is an effective approach for localizing hidden leaks in water supply networks. Relative errors in leakage location depend significantly on head measurement errors, necessitating the use of high-precision pressure gauges with an accuracy class of 0.25 or better. An optimization function, defined as the ratio of the localization relative error to the probability of detection, was used to determine the optimal location for the control section. Dependencies of localization relative error on the pressure gauge accuracy class, section length, and piezometric head are obtained. Presented multi-leakage estimation model enables the assessment of the multi-leakage probability, enhancing decision-making efficiency for emergency repairs in water supply networks.

Research on the measurement mechanism of a six-axis force sensor based on a flexible hinge series–parallel hybrid

Abstract Addressing the common limitations of current six-axis force sensors, including the degradation of strain gauge accuracy due to environmental influences and the necessity for a complete replacement when damaged, this paper proposes an innovative six-axis force sensor that integrates a hybrid serial–parallel structure featuring flexible hinges. The sensor’s bracket is designed using a combination of serial–parallel flexible hinges, which confer load distribution capabilities, are lightweight, have high strength, and facilitate replacement. The static force model and the overall stiffness model of the sensor were developed based on the 3-universal–prismatic–universal parallel mechanism theory, providing a theoretical foundation for evaluating the sensor’s performance. To validate the accuracy of the stiffness model, finite element software is utilized for simulation-based verification. Subsequently, a calibration experiment is performed on the sensor, yielding results that conclusively show an error margin of less than 5% between experimental and theoretical values, satisfying the design criteria for sensor measurement.

What Makes an Excellent Teacher? Insights From Junior High School Students With a History of Disruptive Behavior

Evidence of the powerful relationship between what teachers do and how effectively their students learn has led to reforms aimed at improving the quality of teaching. Most jurisdictions are now paying increased attention both to the initial and ongoing education of teachers, as well as methods to assess, reward and improve quality teaching. Predominant among these methods are frameworks that define observable elements of pedagogical practice for which there is evidence of benefit for student learning, engagement, and behavior. However, we contend that even the best of these do not go far enough, as they do not explicitly consider students with disability, even those students with so-called “high-incidence” disabilities enrolled in everyday classrooms—such as those with Attention Deficit Hyperactivity Disorder and Developmental Language Disorder—whose classroom behavior often indicates that their learning needs are not being met. In this manuscript, we report findings from in-depth interviews with 50 Grade 7–10 students with a history of disruptive and disengaged behavior from three secondary schools serving disadvantaged communities. Responses to the question “what makes an excellent teacher” were coded into four categories. Three of the four categories (emotional support, classroom organization, and instructional support) reflect internationally accepted domains of quality teaching, while the fourth, teachers’ temperament and personality, was added to gauge accuracy of the common belief that this is the element students care most about. Analysis yielded novel results with the majority of students emphasizing instructional support practices that are not well represented in most measures of quality teaching. We argue that these practices represent an essential—but often absent—“top layer” of clarity and accessibility that is necessary for “quality teaching” to be inclusive teaching.

Evaluation of depth gauge accuracy in a canine tibial plateau leveling osteotomy model.

To evaluate the accuracy of six depth gauges used in three tibial plateau leveling osteotomy (TPLO) plate holes. Ex vivo experimental study. Cadaveric canine limbs (n=10), one 25-mm-thick wood board, and one 33.8-mm-diameter polyvinyl chloride (PVC) pipe. A TPLO was performed on 10 canine cadaveric pelvic limbs. Three 3.5-mm plate holes were filled with screws. The remaining three plate holes: a compression hole, a combination compression-locking hole, and a stacked combination compression-locking hole were measured by three observers using six commercial depth gauges and using a micrometer as gold standard. The process was repeated on one wood board and one PVC pipe. Bone measurements collected using two depth gauges with base diameter < 5 mm were smaller than measurements collected using the four depth gauges with base diameter > 5.5 mm (p ranging from < .001 to .038). Mean depth gauge measurements were smaller than micrometer measurements by 2.20 mm for the compression hole, 0.82 mm for the combination hole, and 3.57 mm for the stacked combination hole. Measurement differences among depth gauges were also present for wood board and PVC pipe measurements. Bone measurement variability between depth gauges was less for the combination and compression holes than for the stacked combination hole. Depth gauges lacked accuracy. Measurements differed among gauges and measurement variability varied based on plate hole geometry. Depth gauge measurement accuracy varies based on measuring devices and on 3.5-mm plate hole geometry.

Topology optimization on fuel tank rib structures for fuel sloshing suppression based on hybrid fluid–solid SPH simulation

In this paper, we propose a topology optimization method for aircraft fuel tank structural design to reduce the fuel sloshing effect, which is beneficial for aircraft fuel gauge accuracy and flight safety. The method is applied to optimize the hole layouts in the tank rib to reduce fuel sloshing time, increase stiffness, and guarantee lightweight requirements. Specifically, we introduce a hybrid fluid–solid particle based simulator by modeling the impact and elastic forces between fluid (fuel) and solid (ribs, tank wall), to analysis violent fuel sloshing inside the complicated internal tanks, caused by large angle maneuvers and accelerations of an aircraft. Meanwhile, an effective optimizer is built for the rib design, in which the explicitly controlled hole layouts are projected onto the modeled solid particles, such that the process of finite element meshing and remeshing is no longer needed during each optimization iteration. In this way, our proposed method is able to work with complicated aircraft fuel tanks under violent fuel sloshing conditions. We then use a real aircraft wing tank as design case to validate the proposed framework. The result shows that by the generated layout of rib holes, the fuel sloshing time is shortened by 46%, the maximal fuel gauge error is reduced by 14%, and the maximal center of gravity (CG) shift is reduced by 0.15 m.

A New Experimental Approach for Hydraulic Fracturing Fluid Damage of Ultradeep Tight Gas Formation

The unconventional resources from an ultradeep tight gas reservoir have received significant attention in recent decades. Hydraulic fracturing is the main method for tight gas reservoir development because of its extremely low permeability and porosity. During hydraulic fracturing, high hydraulic fracturing fluid (HFF) that invaded the zone near the fracture face may reduce gas relative permeability significantly and impede gas production. The sources of this damage can be the high capillary pressure (HCP) and the presence of water-sensitive clays (PWC). For tight rock, it is usually infeasible to identify the primary damage mechanism using the traditional steady-state measurement method due to long measurement time and gauge accuracy. In this paper, we present a new experimental approach to identify the primary mechanism of the fracture face damage (FFD) through the application of the pressure transmission method and pressure decay method. Both rock matrix and naturally fractured tight samples (depth 18,000 ft, Tarim field, China) were tested. The experimental results showed that the average high capillary pressure damage indexes ( D HCP ) of rock matrix cores and naturally fractured cores are 94.9% and 92.4%, respectively, indicating severe damage caused by HCP. The average clay-swelling and mobilization (CSM) damage indexes ( D CSM ) of rock matrix cores and naturally fractured cores are 29.6% and 38.4%, respectively, indicating that the damage caused by CSM is lighter than that by HCP. HCP is the primary damage mechanism for the tight sandstone. And the damage degree of the rock matrix cores is higher than that of the naturally fractured core. The proposed procedures can be applied to identify the FFD mechanism of other tight and shale formation and provide insightful fundamental data for HFF optimization.

Pressure gauge accuracy and tire maintenance awareness among vehicle owners in Birnin Kebbi, Nigeria

Aside from human factors, tire blowouts and other tire imperfections are major contributors to the persistently high road accident rate. While tire imperfections are categorized as part of the mechanical factors affecting road accident, the tire maintenance personnel and the vehicle owners' human behavior plays a significant role in ensuring that accidents due to tire imperfections are minimized. Therefore, this study aims to determine the accuracy of the pressure gauges used by tire maintenance personnel, popularly called vulcanizers in Nigeria, and to determine the level of awareness of vehicle owners about the basic information that affects the safe use of tires on the road. The study consists of two stages. The first stage investigates the accuracy of the pressure gauges used by twenty vulcanizers in four different districts in Birnin Kebbi, the northwestern part of Nigeria. The second stage was an online survey regarding the tire maintenance behavior of 87 participants, who were formally educated from Diploma to Ph.D. level. The study's findings showed that about 25% of the vulcanizers do not use pressure gauges to measure air pressure during tire inflation, and less than 17% of the readings taken were accurate. Yet about 60% of the respondents believe that vulcanizers' pressure gauges are reliable and less than 30% of the respondents know that the expiring date of tires is four years in Nigeria. Therefore, there is an urgent need for proper awareness about tire usage and maintenance among the general population. It would also be appropriate to include such basic road safety information in the school curriculum at all levels.

Rain Gauge Accuracy at a High-Altitude Meteorological Station in Cathedral Peak

AbstractAutomatic rain gauges, such as tipping-bucket gauges, have generally replaced manual rain gauges in monitoring networks around the world. Both are susceptible to wind-induced errors. Shield...

A Camera Calibration Method with Large Oblique Angle Machine Vision

In order to ensure the safety of the subway when it stops at the platform, it is necessary to detect the limits of the subway platform. However, the currently used station limit detection tools have large detection errors and low efficiency, and cannot meet the detection requirements. In this paper, a non-contact platform limit detection system based on machine vision is studied, and a new set of comprehensive calibration methods is proposed for the calibration of the camera in the system at large angles. After collecting the images of large multi array points set by camera, the effective calibration area is selected and the reference circle center is extracted from the connected domain and centroid center algorithm. After collecting the images of large multi array points set by camera, the effective calibration area is selected and the reference circle center is extracted from the connected domain and centroid center algorithm. The base circle center is used as the reference point to carry out perspective transformation, and the change matrix is obtained and tested. Finally, the maximum error of pixel calibration is 1.639pixel. It is proved by laboratory and field experiments that the measurement system of this method can obtain the contour geometry of the platform section accurately, and the gauge accuracy is within ±1mm after repeated measurements, and the accuracy of platform height and platform distance can be within ±3mm.

Highway deicing salt dynamic runoff to surface water and subsequent infiltration to groundwater during severe UK winters

Dynamic impact to the water environment of deicing salt application at a major highway (motorway) interchange in the UK is quantitatively evaluated for two recent severe UK winters. The contaminant transport pathway studied allowed controls on dynamic highway runoff and storm-sewer discharge to a receiving stream and its subsequent leakage to an underlying sandstone aquifer, including possible contribution to long-term chloride increases in supply wells, to be evaluated. Logged stream electrical-conductivity (EC) to estimate chloride concentrations, stream flow, climate and motorway salt application data were used to assess salt fate. Stream loading was responsive to salt applications and climate variability influencing salt release. Chloride (via EC) was predicted to exceed the stream Environmental Quality Standard (250mg/l) for 33% and 18% of the two winters. Maximum stream concentrations (3500mg/l, 15% sea water salinity) were ascribed to salt-induced melting and drainage of highway snowfall without dilution from, still frozen, catchment water. Salt persistance on the highway under dry-cold conditions was inferred from stream observations of delayed salt removal. Streambed and stream-loss data demonstrated chloride infiltration could occur to the underlying aquifer with mild and severe winter stream leakage estimated to account for 21 to 54% respectively of the 70t of increased chloride (over baseline) annually abstracted by supply wells. Deicing salt infiltration lateral to the highway alongside other urban/natural sources were inferred to contribute the shortfall. Challenges in quantifying chloride mass/fluxes (flow gauge accuracy at high flows, salt loading from other roads, weaker chloride-EC correlation at low concentrations), may be largely overcome by modest investment in enhanced data acquisition or minor approach modification. The increased understanding of deicing salt dynamic loading to the water environment obtained is relevant to improved groundwater resource management, highway salt application practice, surface-water - ecosystem management, and decision making on highway drainage to ground.

Research on Flatness Signal De-noising Based on Wavelet Theory

On the basis of wavelet transform theory, using computer to simulate ∞atness signal with noise emerging in all kinds of environment, through the analysis of wavelet basis, decomposition scale and threshold rules, the actual ∞atness signal is extracted, which not only provides evidence for the improvement of ∞atness gauge accuracy, but precisely describes ∞atness ∞aw thus laid better foundation for the real-time control of ∞atness.

The Study of Continuous Rolling Mill Inter-stand Tension Inferential Control Systems

The inter-stand tension inferential control systems are used to stabilize the rolling motor torque. To stabilize the motor torque the electric drive system with the properties of the rolling motor torque supply may also be used. An alternate option may include torque stabilization by to the effect on speed of the previous, further or controlled mill stand. The tension control accuracy depends on how exact the unhindered rolling torque is determined. Nevertheless, a change in tension due to this factor may result in improving gauge accuracy in some systems. Using the model of the continuous rolling mill, the paper considers the force interaction between the stand electric drives for different technological conditions of rolling. It analyses the operation of the rolling mill using different system for tension inferential control. The finished studies prove that size alignment is provided with the tension control system affecting speed of the further stands. The paper verifies that the characteristics of the rolling mill including aligning ability depend on the rolling speed. It is a good practice to apply those results during the selection and calculation of the inferential tension controllers.

V単独，V-Nb複合添加超高強度ホットスタンピング部材の組織と機械的性質

As a method for producing ultrahigh strength automotive steel components with high gauge accuracy, the hot stamping technology draws attention and the amount of hot stamped automotive components has exponentially increased in the last decade. The concerns about the potential danger of embrittlement and delayed fracture, however, limit the strength of conventional hot stamped components to 1500 MPa. If these concerns are eliminated, automotive steel components with higher strength which is demanded by the automotive industry can be further commercialized.In this study, microstructures and mechanical properties of V and/or Nb bearing ultrahigh strength hot stamped steel components have been investigated. The V addition improves the resistance to delayed fracture by forming VC whose interface with matrix is supposed to act as preferential hydrogen trap site. The Nb addition refines the microstructure, which improves both the toughness and the resistance to delayed fracture. Proper hot stamping conditions for these steels has been discussed to create an ultrafine martensite microstructure and finely dispersed precipitates. The results indicate that 1900 MPa class steel components with good toughness and high resistance to delayed fracture can be produced.

Measurement accuracy of weighing and tipping-bucket rainfall intensity gauges under dynamic laboratory testing

The contribution of any single uncertainty factor in the resulting performance of infield rain gauge measurements still has to be comprehensively assessed due to the high number of real world error sources involved, such as the intrinsic variability of rainfall intensity (RI), wind effects, wetting losses, the ambient temperature, etc. In recent years the World Meteorological Organization (WMO) addressed these issues by fostering dedicated investigations, which revealed further difficulties in assessing the actual reference rainfall intensity in the field.This work reports on an extensive assessment of the OTT Pluvio2 weighing gauge accuracy when measuring rainfall intensity under laboratory dynamic conditions (time varying reference flow rates). The results obtained from the weighing rain gauge (WG) were also compared with a MTX tipping-bucket rain gauge (TBR) under the same test conditions. Tests were carried out by simulating various artificial precipitation events, with unsteady rainfall intensity, using a suitable dynamic rainfall generator. Real world rainfall data measured by an Ogawa catching-type drop counter at a field test site located within the Hong Kong International Airport (HKIA) were used as a reference for the artificial rain generation system.Results demonstrate that the differences observed between the laboratory and field performance of catching-type gauges are only partially attributable to the weather and operational conditions in the field. The dynamics of real world precipitation events is responsible for a large part of the measurement errors, which can be accurately assessed in the laboratory under controlled environmental conditions. This allows for new testing methodologies and the development of instruments with enhanced performance in the field.

목표치 정형화 및 외란 관측기를 활용한 연속 냉간압연 시스템의 2-자유도 스트립 두께 및 장력 최적 제어기 설계

이 논문은 목표치 정형화 필터와 외란관측기를 활용하여 연속 냉간압연 시스템의 스트립 두께 및 장력에 대한 2-자유도 최적 제어기 설계에 관한 연구를 수행한다. 먼저 게이지 미터식과 후크 법칙을 이용하여 스트립 두께 및 장력에 관한 동적모델을 각각 구축한다. 다음에는 동적모델을 기반으로 2-자유도 제어기를 설계한다. 여기서 피드포워드 제어기는 목표치 정형화 필터와 외란 관측기를 활용한 제어기로 구성되며, 피드백 제어기는 역 최적 제어기로 설계된다. 끝으로 컴퓨터 시뮬레이션을 통하여 이 논문에서 제안한 2-자유도 최적 제어기가 연속 냉간압연 시스템의 기존 제어기보다 스트립 두께 및 장력에 대한 목표치 추종성능과 외란 제거성능이 매우 우수함을 보인다.

Study on the Shifting Model of Edge Drop Control in Ultra-Wide 6-High Tandem Cold Rolling Mill

Edge drop is an important quality evaluating index for strip cross-section with the increasing of requirement for higher gauge accuracy to meet customer's demand. The mathematical model of roll shifting system plays an important role in controlling the edge drop on modern tandem cold rolling mills. Based on the explicit dynamic finite element method, a 3D finite element simulation model of rolls and strip is established for a large ultra-wide 6-high cold rolling mill with the developed EDW (edge drop control work roll) and the matched CVC intermediate roll to investigate the effect of work roll shift on edge drop of strip. Considering on the characteristics of EDW work rolls, equivalent area compensated method has been put forward to build the shifting model for edge drop control. The results indicated that the values of edge drop are less than 7μm by using the proper shifting model and the shifting model can be used to guide the practical production.

Study on the Shifting Model of Edge Drop Control in Ultra-Wide 6-High Tandem Cold Rolling Mill

Edge drop is an important quality evaluating index for strip cross-section with the increasing of requirement for higher gauge accuracy to meet customer's demand. The mathematical model of roll shifting system plays an important role in controlling the edge drop on modern tandem cold rolling mills. Based on the explicit dynamic finite element method, a 3D finite element simulation model of rolls and strip is established for a large ultra-wide 6-high cold rolling mill with the developed EDW (edge drop control work roll) and the matched CVC intermediate roll to investigate the effect of work roll shift on edge drop of strip. Considering on the characteristics of EDW work rolls, equivalent area compensated method has been put forward to build the shifting model for edge drop control. The results indicated that the values of edge drop are less than 7μm by using the proper shifting model and the shifting model can be used to guide the practical production.

Optimal design of a micromachined force gauge under uncertainty

Micromachined force gauges, like many microdevices, are subject to inevitable and inherent uncertainty in dimensional and material parameters that lead to variability in the gauge accuracy and reliability. This paper presents a methodology for the design of a micromachined force gauge under uncertainty, in which the measured force and the maximum stress in the beams in the gauge are related to five uncertain design parameters representing the dimensions of the beam, the material property and the deflection of the beam under the force being measured. A deterministic large-deflection beam model is combined with a sampling-based stochastic model to obtain the distributions of the measured force and the maximum stress corresponding to the interactive influence of the uncertainty in the five design parameters. An optimization problem is formulated to maximize the force measurement accuracy subject to a constraint on the maximum allowable stress. On the basis of the optimization results, design windows for the deflection and the force that maximize the accuracy are derived as functions of the uncertainties in the design parameters. The results provide directly usable information on the optimum geometric design of the force gauge for given uncertainties in the manufacturing and operation of the device.

Implant process control: Going beyond particles and RS

Ion Implant process control has changed considerably over the past 10 years. In the mid 1990s ion implant process control could easily be characterized as a daily dose monitor and particle check. However, as devices have shrunk and become faster, the sensitivity to process variations has increased, requiring a much more sophisticated process control strategy. Traditional test wafer based measurements now include periodic verification of implant angle accuracy, charge control system effectiveness, metals contamination, cross contamination and even ion gauge accuracy that are all known to contribute to process variations. In addition to more varied wafer based process verification methods, the introduction of networked data collection systems has now facilitated the ability to provide process monitoring of virtually every implant for every process recipe run. Automated systems can now monitor implant runs and flag possible out of control situations for review by process and equipment engineers, or depending on the severity of the fault, prevent further processing of material while the fault is investigated. Proper fault detection software and implant parameter databases provide process engineers with powerful tools to use for process optimization, interruption and fault elimination and correlation of tool operation parameters with device performance measurements. As fault detection systems are improved, the need for wafer based process control will decrease, although it is debatable that wafer based process control will ever be completely eliminated.

Pressure measurement repeatability in high current ion implanters using hot cathode ionization gauge with design and operation optimized for stability

Long-term pressure measurement repeatability in high current ion implanters is an important factor for ion beam current measurement and repeatable dose delivery. In the Axcelis GSD® end station, the issue is particularly acute owing to the small volume of the process chamber. High pressure conditions arise during ion beam irradiation of photoresist layers which, in turn, leads to significant ion beam current neutralization. The GSD design employs a “pressure compensation” algorithm (PCOMP) to offset potential ion beam current measurement errors; the success of this technique depends entirely on accurate and repeatable ion gauge pressure measurement. Incorrect pressure measurement directly leads to dose errors. For example, the dose equation using PCOMP tells us that for a modest PCOMP value of 30%, a chamber pressure measurement error of 2.0E−5Torr can result in a dose error of 5% at normal process pressures. Standard hot cathode ion gauges used for pressure measurement are not capable of meeting the requirements for good dose control since gauge to gauge differences are not well controlled and gauge accuracy is only on the order of 30%. Of more consequence is the degradation of gauge response over time. Axcelis introduced the Stabil-Ion® Bayard-Alpert (BA) gauge to improve dose reproducibility through much improved gauge to gauge matching (±6%) and more accurate gauge output. This article discusses the operation of this gauge system in a production environment and its impact on process dose and process trends. The focus of the discussion is directed to a particular ion implanter design (Axcelis GSD®) since it is unique in its dependence on a PCOMP scheme to counter the effects of ion beam neutralization. However, the above gauge or any similarly stabilized BA gauge would be of benefit to the long-term output and process trends of most ion implant systems.