Combination Of Design Features Research Articles

Does pay-for-performance design matter? Evidence from Brazil.

Pay-for-performance (P4P) schemes have been shown to have mixed effects on health care outcomes. A challenge in interpreting this evidence is that P4P is often considered a homogenous intervention, when in practice schemes vary widely in their design. Our study contributes to this literature by providing a detailed depiction of incentive design across municipalities within a national P4P scheme in Brazil [Primary Care Access and Quality (PMAQ)] and exploring the association of alternative design typologies with the performance of primary health care providers. We carried out a nation-wide survey of municipal health managers to characterize the scheme design, based on the size of the bonus, the providers incentivized and the frequency of payment. Using OLS regressions and controlling for municipality characteristics, we examined whether each design feature was associated with better family health team (FHT) performance. To capture potential interactions between design features, we used cluster analysis to group municipalities into five design typologies and then examined associations with quality of care. A majority of the municipalities included in our study used some of the PMAQ funds to provide bonuses to FHT workers, while the remaining municipalities spent the funds in the traditional way using input-based budgets. Frequent bonus payments (monthly) and higher size bonus allocations (share of 20-80%) were strongly associated with better team performance, while who within a team was eligible to receive bonuses did not in isolation appear to influence performance. The cluster analysis showed what combinations of design features were associated with better performance. The PMAQ score in the 'large bonus/many workers/high-frequency' cluster was 8.44 points higher than the 'no bonus' cluster, equivalent to a difference of 21.7% in the mean PMAQ score. Evidence from our study shows how design features can potentially influence health provider performance, informing the design of more effective P4P schemes.

Memory-Efficient and Flexible Detection of Heavy Hitters in High-Speed Networks

Heavy-hitter detection is a fundamental task in network traffic measurement and security. Existing work faces the dilemma of suffering dynamic and imbalanced traffic characteristics or lowering the detection efficiency and flexibility. In this paper, we propose a flexible sketch called SwitchSketch that embraces dynamic and skewed traffic for efficient and accurate heavy-hitter detection. The key idea of SwitchSketch is allowing the sketch to dynamically switch among different modes and take full use of each bit of the memory. We present an encoding-based switching scheme together with a flexible bucket structure to jointly achieve this goal by using a combination of design features, including variable-length cells, shrunk counters, embedded metadata, and switchable modes. We further implement SwitchSketch on the NetFPGA-1G-CML board. Experimental results based on real Internet traces show that SwitchSketch achieves a high Fβ-Score of threshold-t detection (consistently higher than 0.938) and over 99% precision rate of top-k detection under a tight memory size (e.g., 100KB). Besides, it outperforms the state-of-the-art by reducing the ARE by 30.77%\sim99.96%. All related implementations are open-sourced.

Pupil dilation predicts individual self-regulation success across domains

Multiple theories have proposed that increasing central arousal through the brain’s locus coeruleus—norepinephrine system may facilitate cognitive control and memory. However, the role of the arousal system in emotion regulation is less well understood. Pupil diameter is a proxy to infer upon the central arousal state. We employed an emotion regulation paradigm with a combination of design features that allowed us to dissociate regulation from emotional arousal in the pupil diameter time course of 34 healthy adults. Pupil diameter increase during regulation predicted individual differences in emotion regulation success beyond task difficulty. Moreover, the extent of this individual regulatory arousal boost predicted performance in another self-control task, dietary health challenges. Participants who harnessed more regulation-associated arousal during emotion regulation were also more successful in choosing healthier foods. These results suggest that a common arousal-based facilitation mechanism may support an individual’s self-control across domains.

Multi-Objective Design Optimization of the Reinforced Composite Roof in a Solar Vehicle

A multi-step and -objective design approach was used to optimize the photovoltaic roof in a multi-occupant racing vehicle. It permitted to select the best combination of design features (as shapes, widths, angles) in composite structures simultaneously balancing opposite requirements as static strength and dynamic stiffness. An attention to functional requirements, as weight, solar cells cooling and solar energy conversion, was also essential. Alternative carbon fiber-reinforced plastic structures were investigated by finite elements using static and modal analyses in the way to compare several design configurations in terms of natural frequencies, deformations, flexural stiffness, torsional stiffness, and heat exchange surfaces. A representative roof section was manufactured and tested for model validation. A significant improvement respect to the pre-existing solar roof was detected. The final configuration was manufactured and installed on the vehicle.

Are human faces more attractive with glasses?

This article investigates whether a glasses frame, which is symmetrically designed, can be used as an accessory to enhance an individual's facial attractiveness and the affective responses. We carry out a series of experiments using 16 prototypical glasses frame, each of which consists of different combinations of design features. The frames are fitted on one male and one female faces selected from the facial portraits of 200 university students. The participants rate the faces with and without wearing the glasses frames with the 7-point Likert scales on the included perceptual measures. The results show that wearing the glasses frames does generally improve facial symmetry. However, the facial attractiveness is not enhanced accordingly. Some designs such as the glasses frames with smaller rims have less impact on facial attractiveness than those with larger rims. To conclude, artificially improving the facial attractiveness requires more than just an enhancement of facial symmetry.

The Cosmic Background Imager 2

We describe an upgrade to the Cosmic Background Imager instrument to increase its surface brightness sensitivity at small angular scales. The upgrade consisted of replacing the thirteen 0.9-m antennas with 1.4-m antennas incorporating a novel combination of design features, which provided excellent sidelobe and spillover performance for low manufacturing cost. Off-the-shelf spun primaries were used, and the secondary mirrors were oversized and shaped relative to a standard Cassegrain in order to provide an optimum compromise between aperture efficiency and low spillover lobes. Low-order distortions in the primary mirrors were compensated for by custom machining of the secondary mirrors. The secondaries were supported on a transparent dielectric foam cone to minimize scattering. The antennas were tested in the complete instrument, and the beam shape and spillover noise contributions were as expected. We demonstrate the performance of the telescope and the inter-calibration with the previous system using observations of the Sunyaev-Zel'dovich effect in the cluster Abell 1689. The enhanced instrument has been used to study the cosmic microwave background, the Sunyaev-Zel'dovich effect and diffuse Galactic emission.

Parametric study of efficient thermal dissipation in an LED back light unit

PurposeThermal management under high heat flux is crucial to developing high‐power light‐emitting diode (LED) applications. The purpose of this paper is to propose an efficient thermal dissipation technique for an LED back light unit (BLU) system.Design/methodology/approachA typical BLU system includes an LED package (GaN on sapphire, cathode/anode, silicone encapsulant, resin plus phosphor) on a printed circuit board (PCB), a light guide panel, and an aluminum cover frame. The temperature distribution of this system has been simulated and the thermal behavior within a 3D model has been investigated using a commercial computational fluid dynamic code (FLUENT 6.3).FindingsThe authors examined the heat‐spreading effect of cover lengths ranging from 6 to 300 mm and also observed the effect of back cover thickness on the junction temperature and cover frame temperature and investigated the influence of the air gap between the package and the cover frame. Removing the air gap lowers the maximum temperature by about 6 percent. It was found that the addition of a copper layer covering the external surfaces of the LED chip enhanced the cooling efficiency. Finally, the maximum junction temperature can be decreased by more than 21 percent in the range of parameters considered by removing the air gap, adding a heat spreader, and using a thick cover frame.Originality/valueIn this paper, thermal management for efficient heat spreading through a typical BLU system without using any additional devices is investigated. Several parameters that increase the system's temperature are examined, and a combination of design features that attenuate the junction temperature is proposed.

An impedimetric approach for accurate particle sizing using a microfluidic Coulter counter

In this paper, we present the design, impedimetric characterization and testing of a microfabricated Coulter counter for particle size measurement that uses a pair of thin film coplanar Au/Ti electrodes. An electrical equivalent circuit model of the designed device is analyzed. Accurate measurement of particle size was achieved by operating the device at a frequency for which the overall impedance is dominated by the channel resistance. A combination of design features, including the use of a pair of sensing electrodes with a surface area of 100 µm by 435 µm, a spacing of 1785 µm between the two sensing electrodes and a 350 µm long microchannel, ensures that this resistance dominates over a range of relatively low frequencies. The device was characterized for NaCl electrolyte solutions with different ionic concentrations ranging from 10−5 to 0.1 M. Results proved that the resistive behavior of the sensor occurs over a range of relatively low frequencies for all tested concentrations. The Coulter counter was then used to detect 30 µm polystyrene particles at a selected excitation frequency. Testing results demonstrated that the device can accurately measure particle sizes with small error. The design can be extended to ac Coulter counters with sub-micron sensing channels. Analysis of three designs of ac Coulter counters including sub-micron sensing channels using the electrical equivalent circuit model predicts that they can be operated at even lower frequencies, to accurately size nanoscale particles.

Measures for reducing ultra-high-molecular-weight polyethylene wear in total knee replacement: a simulator study / Reduzierter UHMWPE-Abrieb im Rahmen der Knieendoprothetik: eine Simulatorstudie

Wear of ultra-high-molecular-weight polyethylene (UHM-WPE) inlays is associated with aseptic loosening in total knee replacement (TKR). The aim of this study was to investigate the in vitro performance of a TKR system that combines several measures to decrease UHMWPE wear. Tests were carried out on a BPK-S Integration system (R&D, P. Brehm Chirurgie-Mechanik, Weisendorf, Germany) according to ISO 14,243-1 in a knee joint simulator. Calf serum with a high protein concentration of 30 g/l was chosen as the test lubricant. PE wear was measured gravimetrically. Particle analysis was performed by scanning electron microscopy, with measurement of particle size and shape. Low mean wear rates of 1.20 mg per million cycles were found for the fixed bearing type and 2.47 mg per million cycles for the rotating-platform bearing design. Anteroposterior deflection was low. The contact areas for both types of bearings were large and showed a constant pattern throughout the test. Backside wear was obvious on rotating platforms. Particle analysis revealed equally sized and round-shaped particles in both types of bearings (fixed, 0.35 microm; mobile, 0.32 microm). In conclusion, the combination of design features and surface modifications of the BPK-S integration TKR system leads to low gravimetric UHMWPE wear.

Investigating Design Features of Descriptive Graphic Rating Scales

Trained raters used descriptive graphic rating scales (i.e., continuous score scales) to evaluate students' work. The scales incorporated different combinations of design features (i.e., presence or absence of a defined midpoint or hatchmarks or both). The study's purposes were to (a) decide how many points each continuous scale could be considered to have and (b) determine whether different design features affected reliability. The data were analyzed using Facets (Linacre, 1996), a Rasch-based rating scale analysis computer program. In addition, intraclass correlational analyses were run. All the continuous scales could be considered to have at least 5 points, whereas some of the scales could be viewed as having as many as 7 to 10 points. If the scales were considered to have 5 points, then student separation reliabilities ranged from .79 to .91, whereas the intraclass correlation coefficients ranged from .73 to .85. Scales with defined midpoints did not have higher student separation reliabilities or intraclass correlations than scales with no defined midpoints. Similarly, scales with more hatchmarks were no more or less reliable than scales with fewer hatchmarks.

Thin-Film Deposition Via Pulsed Laser Ablation

AbstractWe report on a novel experimental approach for thin-film deposition via pulsed laser ablation. A combination of design features including the incorporation of original sample manipulation methods as well as enhanced analytical capabilities allow for experimental control and flexibility for thin-film deposition studies of a variety of materials. Here, the application is illustrated with a study of 532 nm pulsed laser ablation and subsequent deposition of CdTe.Conditions have been found that produce a mildly energetic ablation plume, and the average kinetic energies for the neutral and ionic ablation species in the plume have been determined to be approximately 2 and 11 eV, respectively. It has been shown that in the presence of an electric field the ionic species can be diverted away from the detector (and subsequently from the eventual deposit). Thin film deposits clearly reveal an increase in the number of sub-micron particles when direct ablation ions contribute to the deposition. The possibility for extraction of ablation ions and preparation of ablation plumes of neutrals only has been clearly demonstrated.

A heterarchical generic discrete manufacturing simulation model and its application in a world class manufacturing environment

Abstract Current factory design and evaluation is very primitive. Factory components are designed in many cases independently. Product and process design are not well integrated. An encompassing framework is needed for iterating through a series of total factory designs, searching for optimal performance. In addition, a vehicle is needed for predicting the performance of a proposed advanced manufacturing system, so that engineers may have a sound means for evaluating such proposals. A heterarchical discrete manufacturing SIMNET II simulation model (SIMCELLS) was developed as a comprehensive methodology for designing and evaluating discrete manufacturing systems. SIMCELLS allows manufacturing systems engineers to experiment with alternative system structures and control strategies while seeking that combination of design features that will produce the desired overall system performance. The model in combination with a modernization programme is enabling a firm to successfully manufacture and sell trucks me...

Survey Errors and Survey Costs.

1. An Introduction to Survey Errors. 1.1 Diverse Perspectives on Survey Research. 1.2 The Themes of Integration: Errors and Costs. 1.3 The Languages of Error. 1.4 Classifications of Error Within Survey Statistics. 1.5 Terminology of Errors in Psychological Measurement. 1.6 The Language of Errors in Econometrics. 1.7 Debates About Inferential Errors. 1.8 Important features of language Differences. 1.9 Summary: The Tyranny of the Measurable. 1.10 Summary and Plan of This Book. 2. An Introduction to Survey Costs. 2.1 Rationale for a Joint Concern About Costs and Errors. 2.2 Use of Cost and Error Models in Sample Design. 2.3 Criticisms of Cost-Error Modeling to Guide Survey Decisions. 2.4 Nonlinear Cost Models Often Apply to Practical Survey Administration. 2.5 Survey Cost Models are Inherently Discontinuous. 2.6 Cost Models Often Have Stochastic Features. 2.7 Domains of Applicability of Cost Models Must Be Specified. 2.8 Simulation Studies Might Be Best Suited to Design Decisions. 2.9 Is Time Money? 2.10 Summary: Cost Models and Survey Errors. 3. Costs and Errors of Covering the Population. 3.1 Definitions of Populations Relevant to the Survey. 3.2 Coverage Error in Descriptive Statistics. 3.3 An Approach to Coverage Error in Analytic Statistics. 3.4 Components of Coverage Error. 3.5 Coverage Problems with the Target Population of Households. 3.6 Measurement of and Adjustments for Noncoverage Error. 3.7 Survey Cost Issues Involving Coverage Error. 3.8 Summary. 4. Nonresponse in Sample Surveys. 4.1 Nonresponse Rates. 4.2 Response Rate Calculation. 4.3 Temporal Change in Response Rates. 4.4 Item Missing Data. 4.5 Statistical Treatment of Nonresponse in Surveys. 4.6 Summary. 5. Probing the Causes of Nonresponse and Efforts to Reduce Nonresponse. 5.1 Empricial Correlates of Survey Participation. 5.2 Efforts by Survey Methodologists to Reduce Refusals. 5.3 Sociological Concepts Relevant to Survey Nonresponse. 5.4 Psychological Attributes of Nonrespondents. 5.5 Summary. 6. Costs and Errors Arising from Sampling. 6.1 Introduction. 6.2 The nature of Sampling Error. 6.3 Measuring Sampling Error. 6.4 Four Effects of the Design on Sampling Error. 6.5 The Effect of Nonsampling Errors on Sampling Error Estimates. 6.6 Measuring Sampling Errors on Sample Means and Proportions from Complex Samples. 6.7 The Debate on Reflecting the Sample Design in Estimating Analytic Statistics. 6.8 Reflecting the Sample Design When Estimating Complex Statistics. 6.9 Summary. 7. Empirical Estimation of Survey Measurement Error. 7.1 A First Estimation of Observational Errors Versus Errors of Nonobservation. 7.2 Laboratory Experiments Resembling the Survey Interview. 7.3 Measures External to the Survey. 7.4 Randomized Assignment of Measurement Procedures to Sample Persons. 7.5 Repeated measurements of the Same Persons. 7.6 Summary of Individual Techniques of Measurement Errors Estimation. 7.7 Combinations of Design Features. 7.8 Summary. 8. The Interviewer as a Source of Survey Measurement Error. 8.1 Alternative Views on the Role of the Observer. 8.2 The Roles of the Survey Interviewer. 8.3 Designs for Measuring Interview Variance. 8.4 Interviewer Effects in Personal Interview Surveys. 8.5 Interviewer Effects in Centralized Telephone Surveys. 8.6 Explaining the Magnitude of Interviewer Effects. 8.7 Summary of Research on Interviewer Variance. 8.8 Measurement of Interviewer Compliance With Training Guidelines. 8.9 Experiments in Manipulating Interviewer Behavior. 8.10 Social Psychological and Sociological Explanations for Response Error Associated with Interviewers. 8.11 Summary. 9. The Respondent as a Source of Measurement Error. 9.1 Components of Response Formation Process. 9.2 The Encoding Process and the Absence of Knowledge Relevant to the Survey Question. 9.3 Comprehension of the Survey Question. 9.4 Retrieval of Information from Memory. 9.5 Judgment of Appropriate Answer. 9.6 Communication of Response. 9.7 Sociological and Demographic Correlates of Respondent Error. 9.8 Summary. 10. Measurement Errors Associated with the Questionnaire. 101 Properties of Words in Questions. 10.2 Properties of Question Structure. 10.3 Properties of Question Order. 10.4 Conclusions About Measurement Error Related to the Questionnaire. 10.5 Estimates of Measurement Error from Multiple Indicator Models. 10.6 Cost Models Associated with Measurement Error Through the Questionnaire. 10.7 Summary. 11. Response Effects of the Mode of Data Collection. 11.1 Two Very Different Questions About Mode of Data Collection. 11.2 Properties of Media of Communication. 11.3 Applying Theories of Mediated Communication to Survey Research. 11.4 Findings from the Telephone Survey Literature. 11.5 Interaction Effects of Mode and Other Design. 11.6 Survey Costs and the Mode of Data Collection. 11.7 Cost and Error Modeling with Telephone and Face to Face Surveys. 11.8 Summary. References. Index.

Survey Errors and Survey Costs.

1. An Introduction to Survey Errors.1.1 Diverse Perspectives on Survey Research.1.2 The Themes of Integration: Errors and Costs.1.3 The Languages of Error.1.4 Classifications of Error Within Survey Statistics.1.5 Terminology of Errors in Psychological Measurement.1.6 The Language of Errors in Econometrics.1.7 Debates About Inferential Errors.1.8 Important features of language Differences.1.9 Summary: The Tyranny of the Measurable.1.10 Summary and Plan of This Book.2. An Introduction to Survey Costs.2.1 Rationale for a Joint Concern About Costs and Errors.2.2 Use of Cost and Error Models in Sample Design.2.3 Criticisms of Cost-Error Modeling to Guide Survey Decisions.2.4 Nonlinear Cost Models Often Apply to Practical Survey Administration.2.5 Survey Cost Models are Inherently Discontinuous.2.6 Cost Models Often Have Stochastic Features.2.7 Domains of Applicability of Cost Models Must Be Specified.2.8 Simulation Studies Might Be Best Suited to Design Decisions.2.9 Is Time Money?2.10 Summary: Cost Models and Survey Errors.3. Costs and Errors of Covering the Population.3.1 Definitions of Populations Relevant to the Survey.3.2 Coverage Error in Descriptive Statistics.3.3 An Approach to Coverage Error in Analytic Statistics.3.4 Components of Coverage Error.3.5 Coverage Problems with the Target Population of Households.3.6 Measurement of and Adjustments for Noncoverage Error.3.7 Survey Cost Issues Involving Coverage Error.3.8 Summary.4. Nonresponse in Sample Surveys.4.1 Nonresponse Rates.4.2 Response Rate Calculation.4.3 Temporal Change in Response Rates.4.4 Item Missing Data.4.5 Statistical Treatment of Nonresponse in Surveys.4.6 Summary.5. Probing the Causes of Nonresponse and Efforts to Reduce Nonresponse.5.1 Empricial Correlates of Survey Participation.5.2 Efforts by Survey Methodologists to Reduce Refusals.5.3 Sociological Concepts Relevant to Survey Nonresponse.5.4 Psychological Attributes of Nonrespondents.5.5 Summary.6. Costs and Errors Arising from Sampling.6.1 Introduction.6.2 The nature of Sampling Error.6.3 Measuring Sampling Error.6.4 Four Effects of the Design on Sampling Error.6.5 The Effect of Nonsampling Errors on Sampling Error Estimates.6.6 Measuring Sampling Errors on Sample Means and Proportions from Complex Samples.6.7 The Debate on Reflecting the Sample Design in Estimating Analytic Statistics.6.8 Reflecting the Sample Design When Estimating Complex Statistics.6.9 Summary.7. Empirical Estimation of Survey Measurement Error.7.1 A First Estimation of Observational Errors Versus Errors of Nonobservation.7.2 Laboratory Experiments Resembling the Survey Interview.7.3 Measures External to the Survey.7.4 Randomized Assignment of Measurement Procedures to Sample Persons.7.5 Repeated measurements of the Same Persons.7.6 Summary of Individual Techniques of Measurement Errors Estimation.7.7 Combinations of Design Features.7.8 Summary.8. The Interviewer as a Source of Survey Measurement Error.8.1 Alternative Views on the Role of the Observer.8.2 The Roles of the Survey Interviewer.8.3 Designs for Measuring Interview Variance.8.4 Interviewer Effects in Personal Interview Surveys.8.5 Interviewer Effects in Centralized Telephone Surveys.8.6 Explaining the Magnitude of Interviewer Effects.8.7 Summary of Research on Interviewer Variance.8.8 Measurement of Interviewer Compliance With Training Guidelines.8.9 Experiments in Manipulating Interviewer Behavior.8.10 Social Psychological and Sociological Explanations for Response Error Associated with Interviewers.8.11 Summary.9. The Respondent as a Source of Measurement Error.9.1 Components of Response Formation Process.9.2 The Encoding Process and the Absence of Knowledge Relevant to the Survey Question.9.3 Comprehension of the Survey Question.9.4 Retrieval of Information from Memory.9.5 Judgment of Appropriate Answer.9.6 Communication of Response.9.7 Sociological and Demographic Correlates of Respondent Error.9.8 Summary.10. Measurement Errors Associated with the Questionnaire.101 Properties of Words in Questions.10.2 Properties of Question Structure.10.3 Properties of Question Order.10.4 Conclusions About Measurement Error Related to the Questionnaire.10.5 Estimates of Measurement Error from Multiple Indicator Models.10.6 Cost Models Associated with Measurement Error Through the Questionnaire.10.7 Summary.11. Response Effects of the Mode of Data Collection.11.1 Two Very Different Questions About Mode of Data Collection.11.2 Properties of Media of Communication.11.3 Applying Theories of Mediated Communication to Survey Research.11.4 Findings from the Telephone Survey Literature.11.5 Interaction Effects of Mode and Other Design.11.6 Survey Costs and the Mode of Data Collection.11.7 Cost and Error Modeling with Telephone and Face to Face Surveys.11.8 Summary.References.Index.

COMBATANT SHIP DESIGN GUIDANCE THROUGH MISSION EFFECTIVENESS ANALYSIS

ABSTRACTA combatant ship design technique is described that provides guidance for new designs and can assist in evaluating current designs and their revisions. The technique attempts to provide design evaluations by comparing competing designs in a mission performance context. For a selected mission, a number of ship alternatives are selected for study. Task groups are then selected to carry out the mission. The ship characteristics are determined to match each of the ship alternatives including size, first cost and life cycle cost. Then the task groups are put through a simulated mission including enemy attack (defense by the group) and their offensive mission. The losses resulting from enemy action and the performance of the group in carrying out their mission are computed for various enemy threats. Measures of effectiveness, both for the mission itself and the ship operating in a peacetime format are then determined. For the mission, the effectiveness is defined as the percent of mission completion divided by the total mission cost (including all ship operations and losses). For the peacetime mode, two measures of effectiveness are determined: ship capability per unit of first cost and ship capability per unit of life cycle cost. The relative merits of each design selection, whether it be combat system, survivability feature, or subsystem selection or combinations of design features can be assessed in a systematic way. Design guidance is directly forthcoming.Several full examples are examined including a strike mission and an amphibious assault operation. The value of different ship types, armor, radar cross section reductions, task group compositions and missile allocations between defensive and offensive use are examined. Conclusions are drawn and the usefulness of the approach is analyzed.

Thermal Expansion Accommodation in a Jet Engine Frame

A prime consideration in the design of turbomachinery hot section structural frames is thermal fatigue caused by differential heating of the frame basic structural elements. This paper describes the general thermal deflection pattern of a frame and some design features which can accommodate this relative expansion without excessive stress. Also discussed is a particular combination of design features which provide increased tolerance for thermal expansion while maintaining a large mechanical stiffness as is often required for a high bypass ratio turbofan engine application. This unique combination of frame design features, developed under NASA contract NAS3-20643 to NASA-Lewis Research Center with Mr. Carl C. Ciepluch as the Lewis Project Manager, represents a significant contribution to state of the art frame design.

Two improved simple instruments for measuring low frost-points

Two inexpensive cooled-mirror instruments have been designed for the determination of dew-points and frost-points down to -50 degrees C or lower with an accuracy of approximately +or-1 degrees C at that order of frost-point. Measurement errors and effects of operator technique have been made small, firstly by a combination of design features and secondly by a modified method of interpreting the temperature readings. In addition, in one of the two instruments described observational difficulties have been minimized by a design that results in one localized cold spot of accurately measured temperature on an otherwise apparently unbroken mirror surface; this latter instrument is particularly suitable for site use and by inexperienced personnel.