Mounting Height Research Articles

The influence of range hood mounting height on capture efficiency

A new test procedure for determining capture efficiency (CE) of domestic range hoods (ASTM-E3087.18) was used to investigate how the range hood mounting height above a stove influences CE. Previous studies on CE utilized only two heights for a single range hood and a test procedure that did not strictly adhere to ASTM-E3087.18. In the study reported herein, testing was performed in accordance with ASTM-E3087.18 on six range hoods of similar design at three heights. The measured CE values ranged from 42.8–96.2%CE with CE changing by 8.2%CE at worst when varying the height for a specific fan. The influence of mounting height on CE uncertainty, repeatability, reproducibility and variability were also investigated. Lower mounting heights were found to increase CE and reduce uncertainty at the cost of increased variability between repeat tests. In contrast, intermediate mounting heights typically improved variability performance and repeatability/reproducibility. One range hood with vents for re-circulation showed higher uncertainty and more variability, indicating that flow exhausting from these vents can influence CE performance. Thus, it is possible that future ASHRAE/HVI certification standards be written with re-circulating vents sealed off during testing and a specified mounting height to minimize variations in CE caused by varying mounting heights.

Online crop height and density estimation in grain fields using LiDAR

Crop height and density estimation ahead of the combine harvester have been investigated over the last 30 years, but they remain a challenge. LiDAR technology is increasingly being investigated for phenotyping and monitoring of cereals. However, so far, little has been published about the influence of laser mounting position and robust online measurement of height and density from a single LiDAR scan. Therefore, the influence of the angle and height of the LiDAR mounting on crop height and density estimation in wheat and barley was investigated in this study. Tests were conducted in different crop heights, densities, moisture levels and varieties. The crop height was estimated with a root mean squared error of 0.082 m at an angle of 90° between the LiDAR scanning plane and the horizontal. Two methods were compared for crop density estimation. The inter-percentile and the transversal variance method both successfully predicted the crop density, but the variance based method performed better with a coefficient of determination (R2) of 0.77 and a root mean squared error of 82 g [dry ears] m-2. When considering only one variety, the performance improved to reach an R2 of 0.8 and a root mean squared error of 44 g [dry ears] m-2. Variation in mounting angle of the sensor had less effect on the prediction accuracy than the mounting height.

In-field characterization of key performance parameters for bifacial photovoltaic installation in a desert climate

Abstract To address the main challenges inhibiting the adoption of bifacial PV technology in hot desert environment, continuous performance monitoring and comprehensive analyses are timely required. Therefore, for strengthening its bankability, this techno-economic study presents an in-field bifacial parametric analysis for the environment of Middle-East. Impacts of ground coverage ratio (GCR), stand-alone/in-array mounted losses, albedo, module temperature, mounting height, tilt, and azimuth angle were quantified. To highlight the bifacial potential, economic analysis as a function of energy gain and investment premium was carried out for demarcating profitable operating zones. Moreover, multi-variable analysis for rear irradiance was performed using ground coverage ratio, height, albedo and array size, specifically:1 × 1 (free-standing module), 3 × 3 and 5 × 5. It was found that for systems where the land costs are significant, high GCR coupled with increased mounting height would result in a better energy yield per area. Module with a bifacial gain of 8.6% was found to be profitable provided that the bifacial premium investment doesn’t exceed 10% of monofacial. Thermally, bifacial power gain was found to determine the cell temperature under different irradiation conditions. The study reveals vital insights that will allow engineers and researchers to optimize bifacial PV performance in hot and sunny desert climates.

Energy yield of bifacial textured perovskite/silicon tandem photovoltaic modules

Bifacial perovskite/crystalline silicon (c-Si) tandem photovoltaic (PV) modules that harvest albedo radiation are a promising strategy to further enhance the energy yield (EY) of monofacial perovskite/c-Si tandem PV modules. Given the required current matching in bifacial perovskite/c-Si two-terminal (2T) tandem PV modules, predicting the expected enhancement in EY requires an advanced EY modelling framework. In this study, the architecture, module tilt, perovskite absorber layer thickness, and bandgap of the perovskite top solar cell are optimized for several types of grounds and two locations. Compared to bifacial c-Si single-junction PV modules, the relative enhancement in EY of textured bifacial perovskite/c-Si 2T tandem PV modules is around 24–38% for an exemplary grass ground (mean albedo = 35%). With increasing albedo, the optimum bandgap of the perovskite top solar cell decreases from 1.72 eV (black ground, mean albedo = 0%) to 1.55 eV (snow, mean albedo = 88%). This is attributed to enhanced current generation only in the c-Si bottom solar cell due to albedo radiation, entering the solar cell at the rear side. In addition, minor optical losses due to ground shading are found for modules with a finite mounting height in the range of 1 m. Overall, our study highlights the importance of EY modelling to assess the performance of bifacial perovskite/c-Si tandem PV. It provides direction for the design of bifacial perovskite/c-Si tandem solar cells with regard to the device architecture and the choice of the perovskite material with regard to its bandgap.

Deposition of solid particles exposed to the suction of dual pumps in the tank of a pumping station

The present study aims to reveal solid-liquid two-phase flow patterns in a pumping station which is featured by the deployment of two pumps in a cylindrical tank. The computational fluid dynamics technique (CFD) was used to simulate the flows. The numerical scheme constructed was validated through solid particle velocity measured using a phase Doppler particle analyzer (PDPA). Effects of the inter-pump distance and the mounting height of the pumps were investigated. The results indicate that the flow in the tank is dominated by large-scale flow structures. In vertical direction, solid particles experience three distinct stages, namely acceleration, velocity stabilization and velocity declining stages. As the space between the two pumps is enlarged, the dispersion of solid particles at the tank bottom is promoted. With increasing mounting height of the two pumps, discrepancy of solid-phase concentration between the two pump inlet sections is enhanced, improving the risk of solid particle deposition.

Modeling and Dynamic-Simulating the Water Distribution of a Fixed Spray-Plate Sprinkler on a Lateral-Move Sprinkler Irrigation System

Uniformity of water distribution plays an important role in evaluating irrigation quality. As necessities in calculating irrigation uniformity during designing a lateral-move sprinkler irrigation system (LMSIS), the water distribution patterns of individual sprinkler in motion are crucial. Considering the limitation of the experiment platform, dynamic water distribution of an isolated sprinkler is difficult to measure, especially for a fixed spray plate sprinkler (FSPS) which LMSIS has been widely equipped with in China, therefore developing a model to simulate dynamic water distribution of a moving sprinkler is necessary. The objective of this study was to develop and validate the theoretical basis for calculating water distribution characteristics of a single FSPS in translational motion applying a superposition method, and provide an optimized operation management of LMSIS. The theoretical model’s validity was verified in an indoor experiment using a Nelson D3000 FSPS in motion with 36 grooves and blue-plate spray heads. The software was programmed using the Eclipse Platform and the software was capable of simulating water distribution pattern and Christiansen uniformity coefficient (Cu). The results indicated that the water distribution simulated by the software presents three peaks of maximum application under varying conditions, and the value of water application peaks decreased as working pressure and/or mounting height increased. Conversely, the wetted diameter increased as working pressure and/or mounting height increased. Working pressure, mounting height, and sprinkler spacing each had a significant effect on the Cu. The Cu increased as working pressure and/or mounting height increased but decreased as sprinkler spacing increased. As a consequence, the model can be used to predict the relative water distribution pattern; and the Cu can be calculated with the simulated data, thus providing a tool for designing a new LMSIS.

Evaluation method and reduction measures for the flicker effect in road lighting using fixed Low Mounting Height Luminaires

Low Mounting Height Luminaires (LMHL) are used in many cities on viaducts, cross-sea and cross-river bridges due to their unique advantages. However, the flicker effect is an important factor that needs to be considered in road lighting using fixed LMHL. At present, there are not many researchers in the field of international lighting. Previous types of road lighting design were based on the method of the tunnel lighting flicker effect. At the same time, the flicker effect is mainly based on the subjective feelings of people but is not quantified. In this paper, the Flicker Index (FI) is calculated by measuring the parameters of streetlamps to evaluation flicker effect. Secondly, the suggestion to offset the flicker effect in CIE 88-2004 “Guide for the Lighting of Road Tunnels and Underpasses” is to limit the speed of the vehicle and adjust the road light spacing to avoid the flicker sensitive area on human eyes, while ignoring the essential problem of how the flicker effect is generated through the energy level of the stimulating optical signal. Two factors affecting the strength of the flicker effect are proposed: energy ratio and duty cycle. The duty cycle, in time, refers to the proportion of the strong and weak flashing signals during the period; in space, it refers to the proportional relationship between the length of the luminaire and the distance between the lamps, which is related to the running speed of the vehicle. It is consistent with the CIE recommendations for flicker. Thirdly, the essence of the flicker effect is the problem of the energy level of the stimulus signal. This study investigated the reduction in the brightness of the light source, hence reducing the energy of the visual stimulation signal to the human eye in order to judge the degree of fatigue in human vision. The experimental results show that the degree of fatigue in human vision decreases when the brightness of the experimental light source decreases. Therefore, the key to changing the flicker effect of LMHL is to reduce the contrast between the surface brightness of the luminaire and the brightness of the spatial background.

Manual for Assessing Safety Hardware Crash Testing and Evaluation of Multiple Mailbox Supports for Use with Locking Architectural Mailboxes

With increasing concern about mail-identity theft, there is a growing demand among homeowners and businesses for the use of locking mailboxes for theft deterrence and resistance to vandalism. Lockable mailbox products can be significantly larger and heavier than standard lightweight mailboxes. Therefore, the Texas Department of Transportation (TxDOT) requested evaluation of their crashworthiness before permitting their use on the state highway system. Under TxDOT Project 9-1002-12, crash tests were performed following the Manual for Assessing Safety Hardware (MASH) guidelines and procedures to assess the impact performance of lockable, secure mailboxes in both single and multiple mount configurations. Testing of the larger and heavier locking mailboxes on multiple-mount support posts was unsuccessful owing to vehicle windshield deformation and intrusion. This paper describes the efforts to develop and evaluate the crashworthiness of new proposed designs for multiple mailbox supports used with a combination of lockable and standard mailboxes. The crash tests were performed following MASH guidelines and the evaluation criteria. Two proposed designs were evaluated through full-scale crash testing. Both systems satisfied all required MASH evaluation criteria at low and high impact speeds using a passenger car, which was considered to be the critical design vehicle based on the mailbox mounting height.

Optimisation of installation parameters of subsoiler’ wing using the discrete element method

Optimisation of wing installation parameters of a subsoiler is essential for disrupting hardpans, avoiding excessive disturbance of top soil and improving soil loosening efficiency in conservation tillage. In this study, three key wing installation parameters (the upward angle φ, the mounting height h and the mounting angle β) were optimised using the discrete element method (DEM). Two objectives (soil loosening efficiency η and soil disturbance area ratio κ) were selected for the optimisation. The results showed that the φ affected the η the most, followed by the h, and the β. The significance for the influence of wing parameters on the κ followed the order: the h, the φ, and the β; the effect of φ and h interaction on κ was also significant. To maximise both the κ and the η, h and φ should be appropriately reduced and β should be increased appropriately. The optimal values concerning the η and κ maximization are −6.6°, 34.2° and 87.5 mm, respectively, for the φ, the β, and the h. The overall working performance of the subsoiler with optimal wing parameters was the best as indicated by greater η and κ. The model was able to predict soil disturbance characteristics resulting from the subsoiler with relative errors under 15%. The findings in the present study can have implications for optimising the winged subsoiler on aspects of water conservation and soil loosening efficiency.

Recommended Mounting Heights for Freestanding On-Premise Signs

Freestanding on-premise signs are commercial signs that are not attached to buildings or other structures and include ground-mounted, monument, pylon, and pole signs. This report focuses on issues related to the appropriate mounting height of freestanding signs. The objective of this report is to develop best practices for optimal freestanding on-premise sign mounting height based on roadway factors, sign visibility, and traffic safety, relying on existing research and practice and basic geometry, and describing variations for different road types and sign lateral offsets. To achieve this, the existing on-premise and traffic sign mounting height research was reviewed, and the current state-of-the-practice was summarized. In addition, a technical analysis of on-premise sign height and sign visibility based on roadway cross-section and driver-to-sign sightlines was conducted.

Pedestrian Height Estimation and 3D Reconstruction Using Pixel-resolution Mapping Method Without Special Patterns

Extracting the three-dimensional (3D) information including location and height of a pedestrian is important for vision-based intelligent traffic monitoring systems. This paper tackles the relationship between pixels′ actual size and pixels′ spatial resolution through a new method named pixel-resolution mapping (P-RM). The proposed P-RM method derives the equations for pixels′ spatial resolutions (XY-direction) and object′s height (Z-direction) in the real world, while introducing new tilt angle and mounting height calibration methods that do not require special calibration patterns placed in the real world. Both controlled laboratory and actual world experiments were performed and reported. The tests on 3D mensuration using proposed P-RM method showed overall better than 98.7% accuracy in laboratory environments and better than 96% accuracy in real world pedestrian height estimations. The 3D reconstructed images for measured points were also determined with the proposed P-RM method which shows that the proposed method provides a general algorithm for 3D information extraction.

PEMASANGAN ALAT PEMADAM API RINGAN DI PT E-T-A INDONESIA

Fire extinguisher is one of active protection that effectively used to extinguish at the incipient of the fire. Installation of fire extinguisher were urgently needed to support a company’s efforts to control fire. The purpose of this study was to learn about appropriate the installation of fire extinguisher in PT. E-T-A Indonesia with Peraturan Menteri Tenaga Kerja dan Transmigrasi No. PER.04/MEN/1980. This study was a descriptive research. The primary data obtained by interviews, observation and measurements in the field. Data collected were analyzed descriptively using narration and tabulation. In addition, secondary data were also obtained from documents at PT. E-T-A Indonesia. The research result was the company did not have a spesific policy but the installation of fire extinguisher had been applicated. PT. E-T-A Indonesia had 36 pieces of fire extinguisher with 23 dry chemical powder type and 13 carbon dioxide (CO2) type, which has capacity 3–6 kgs. Implementation of the fire extinguisher insatallation was not accordance with requirements in terms by the distance of each fire extinguisher, fire extinguisher mounting height, and sign to declare fire extinguisher. Based on the research result, it was recommended that the company to make specific policy about the installation of the fire extinguisher. Therefore, the implementation of installation of the fire extinguisher at PT. E-T-A Indonesia more appropriate with Peraturan Menteri Tenaga Kerja dan Transmigrasi No. PER.04/MEN/1980.Keywords: installation, fire, fire extinguisher

EVALUASI PEMASANGAN DAN PEMELIHARAAN ALAT PEMADAM API RINGAN DI GRESIK

Oil and gas industry is an industry sector that has a high risk of fire. Fire is a potential hazard which can caused material loss, break of the production process and the danger to the human life safety. The aim of this research is to evaluate the installation and maintenance of portable fire extinguisher in PT. Pertamina Lubricants Production Unit Gresik. This research was observational and descriptive research using cross sectional design. The data used are primary data obtained from observations and interviews, and secondary data from documents and other supporting reports. The result showed that management has provided portable fire extinguisher almost every corner of the office building and production areas. The results of the identification of a potential fire hazard in PT. Pertamina Lubricants Production Unit Gresik that there is a potential fire hazard group A (solid materials, except metal), group B (material flammable liquid or gas) and group C (voltage electrical installations). Variables which have been in accordance with Decree of Minister of Labor No.04/MEN/1980 is the type and condition, within the installation, and the suitability of portable fire extinguisher signs, while variable that does not fit is the mounting height, sign mounting height and maintenance of portable fire extinguisher. The conclusion is PT. Pertamina Lubricants Production Gresik Unit has carried out the installation and maintenance of portable fire extinguishers but some are not in accordance with the regulations.Keywords: fire, installation, maintenance, portable fire extinguisher

AutoCalib

Emerging smart cities are typically equipped with thousands of outdoor cameras. However, these cameras are usually not calibrated, i.e., information such as their precise mounting height and orientation is not available. Calibrating these cameras allows measurement of real-world distances from the video, thereby enabling a wide range of novel applications such as identifying speeding vehicles and city road planning . Unfortunately, robust camera calibration is a manual process today and is not scalable. In this article, we propose AutoCalib, a system for scalable, automatic calibration of traffic cameras. AutoCalib exploits deep learning to extract selected key-point features from car images in the video and uses a novel filtering and aggregation algorithm to automatically produce a robust estimate of the camera calibration parameters from just hundreds of samples. We have implemented AutoCalib as a service on Azure that takes in a video segment and computes the camera calibration parameters. Using video from real-world traffic cameras, we show that AutoCalib is able to estimate real-world distances with an error of less than 12%.

The Visual Perception of The Car Drivers Dealing with The Road Supporting Facilities, Road Median, Potholes, and Other Cars on a Freeways With and Without Lighting

This study evaluated the existing road lighting on Cikampek and Cipularang freeways. Some of the toll roads have no lighting while some do. The toll road has many uphill, downhill and curve or the combination of those. This paper discusses the motorist’s perception in the toll road that has lighting and no lighting toward the road supporting facilities, median road, potholes, and other Cars. The results show that motorists have better visual perception in the presence of lighting rather than no lighting condition in recognizing traffic sign and road marking, although there are some insignificant conditions. The presence of lighting also provides a good visual perception to recognize the existence road median, potholes, and other cars. The existing condition of the road lighting on Cikampek Cipularang freeways which does not follow the SNI standard (Indonesia Lighting Standard) are greatly affect the motorist’s perception. The existing condition on Cikampek Cipularang freeways has the value of Eav between 6-10 Lux, using HPS lamp and LED lamp that use single sided lighting arrangement with each has different mounting height and luminaire arrangement. We conclude that rearrangement is required to obtain a standardized photometric parameter for the Cikampek-Cipularang freeways.

2D-PIV measurement of range hood-driven flow in a domestic kitchen

High-performance range hoods can quickly exhaust cooking smoke and fumes outdoors. Quantifying the detailed information that range hood-driven flow provides can be an essential prerequisite to optimize the hood's performance. Direct measuring instruments cannot easily determine the velocity due to large velocity gradients and high temperatures. Particle image velocimetry (PIV) is a non-intrusive velocimeter-based method with high spatial resolution and in a global domain. Thus, we applied large-scale 2D-PIV and measured the range hood-driven flow in three sections under isothermal and heating conditions. This study systematically investigated the influence of the exhaust flow rate and mounting height on the range hood-driven flow. The measurement results under isothermal conditions show the actual airflow driven by a range hood cannot be characterized as a simple exhaust and have self-similarity for different exhaust airflow rates. The results also indicate that the mounting height only slightly impacts the velocity boundary conditions of the range hood exhaust surface. The results under the heating conditions clearly reveal that the time-averaged spill length is larger than the average value of the dynamic spill length. This phenomenon indicates that the relationship between time-averaged velocity fields and spill length is not a simple linear scaling relationship. The unsteady flow in the kitchen should be considered to determine the true capture efficiency. Moreover, uncertainty analysis ensures that the benchmark flow data for the follow-up kitchen environment and range hood design simulations.

Effects of surface reflectance and lighting design strategies on energy consumption and visual comfort

Globally, artificial lighting accounts for a considerable part of electrical energy consumption in buildings. Hence, there is a need to design appropriate lighting scenarios for buildings in a way to reduce energy while meeting visual comfort requirements. This research aims to investigate the effects of applying different design strategies on lighting energy use and visual comfort level. Surface finishing reflectance, type, number and mounting height of luminaires are variables in the study. Lighting design software DIALux evo 7.0 provides simulations of a real scale room according to different scenarios whose models were calibrated and validated using experimental field data. The findings indicate that the type of luminaire is the most decisive parameter in quantity and quality of light in an indoor environment. However, increasing the indoor surface reflectance plays a key role in improving energy efficiency and visual comfort. The results show the possibility of electrical energy savings up to 45% by increasing surface reflectance properties. Finally, this paper stresses that there is no single design solution to guarantee both low energy demand and high visual quality, therefore integrating different strategies based on the type of task and the occupant’s activities is highly recommended.

Effects of Mounting Height, Offset Distance, and Number of Light Towers on Drivers’ Visual Performance and Discomfort Glare in Work Zones

Portable light towers are a significant source of glare to motorists entering a work zone. Although existing research has evaluated the effect of light tower orientation on visibility and glare, the effects of factors like mounting height, offset distance from the roadway, and number of light towers in the work zone, on visual performance and discomfort glare is not known. Understanding these relationships can help in developing illuminating guidelines for work zones that can reduce glare for drivers. The goal of this paper is to understand the effect of mounting height, offset distance to the roadway, and number of light towers in the work zone on drivers’ visual performance and discomfort glare. Participants drove through a realistic work zone and evaluated portable light towers in varying mounting heights, offset distances, and number of light towers in the work zone. Results showed that the mounting height and offset distances play a critical role in affecting the driver’s visual performance and discomfort glare rating. Portable light towers, irrespective of wattage and lumen output, at lower than a mounting height of 20 ft and closer to the roadway result in decreasing driver visual performance and increasing their discomfort glare. Portable light towers should be mounted at a height of at least 20 ft and balloon light towers with higher wattage (4,000 W and greater) and lumen output (400,000 lumens and greater) should be located at an offset distance of at least 10 ft from the roadway.

2C4-1 The effect of the mounting height of acoustic traffic signal on road crossing behavior of visually-impaired pedestrian

2C4-1 The effect of the mounting height of acoustic traffic signal on road crossing behavior of visually-impaired pedestrian

Quantifying and Mitigating Wind‐Induced Undercatch in Rainfall Measurements

AbstractDespite the apparent simplicity, it is notoriously difficult to measure rainfall accurately because of the challenging environment within which it is measured. Systematic bias caused by wind is inherent in rainfall measurement and introduces an inconvenient unknown into hydrological science that is generally ignored. This paper examines the role of rain gauge shape and mounting height on catch efficiency (CE), where CE is defined as the ratio between nonreference and reference rainfall measurements. Using a pit gauge as a reference, we have demonstrated that rainfall measurements from an exposed upland site, recorded by an adjacent conventional cylinder rain gauge mounted at 0.5 m, were underestimated by more than 23% on average. At an exposed lowland site, with lower wind speeds on average, the equivalent mean undercatch was 9.4% for an equivalent gauge pairing. An improved‐aerodynamic gauge shape enhanced CE when compared to a conventional cylinder gauge shape. For an improved‐aerodynamic gauge mounted at 0.5 m above the ground, the mean undercatch was 11.2% at the upland site and 3.4% at the lowland site. The mounting height of a rain gauge above the ground also affected CE due to the vertical wind gradient near to the ground. Identical rain gauges mounted at 0.5 and 1.5 m were compared at an upland site, resulting in a mean undercatch of 11.2% and 17.5%, respectively. By selecting three large rainfall events and splitting them into shorter‐duration intervals, a relationship explaining 81% of the variance was established between CE and wind speed.