Estimation of the error factors in irradiance measurements of electromagnetic sources inside disinfection cabinets.

On the effect of cover tilt angle of the simple solar still on its productivity in different seasons and latitudes

This work studies the effect of the tool tilt angle on the generated heat and the material flow in the work pieces joint by Friction Stir Welding (FSW). An apropos kinematic framework together with a two-stage speed-up strategy is adopted to simulate the FSW problem. The effect of tilt angle on the FSWelds is modeled through the contact condition by modifying an enhanced friction model. A rotated friction shear stress is proposed, the angle of rotation depending on the process parameters and the tilt angle. The proposed rotation angle is calibrated by the experimental data provided for a tilt angle 2.5°. The differences of generated heat and material flow for the cases of tool with tilt angle of 0° and 2.5° are discussed. It is concluded that due to the higher temperature, softer material and greater frictional force in the trailing side of the tool, the material flow in the rear side of the FSW tool with the title angle is considerably enhanced, which assists to prevent the generation of defect.

Automobile, aerospace, and shipbuilding industries are looking for lightweight materials for cost effective manufacturing which demands the welding of dissimilar alloy materials. In this study, the effect of tool rotational speed, welding speed, tilt angle, and pin depth on the weld joint were investigated. Aluminum 5052 and 304 stainless-steel alloys were joined by friction stir welding in a lap configuration. The design of the experiments was based on Taguchi’s orthogonal array for conducting the experiments with four factors and three levels for each factor. The microstructural analysis showed tunnel defects, micro voids, and cracks which formed with 0° and 1.5° tilt angles. The defects were eliminated when the tilt angle increased to 2.5° and a mixed stir zone was formed with intermetallic compounds. The presence of the intermetallic compounds increased with the increase in tilt angle and pin depth which further resulted in obtaining a defect-free weld. Hooks were formed on either side of the weld zone creating a mechanical link for the joint. A Vickers hardness value of HV 635.46 was achieved in the mixed stir zone with 1000 rpm, 20 mm/min, and 4.2 mm pin depth with a tilt angle of 2.5°, which increased by three times compared to the hardness of SS 304 steel. The maximum shear strength achieved with 800 rpm, 40 mm/min, and a 4.3 mm pin depth with a tilt angle of 2.5° was 3.18 kN.

Effect of different curing times and distances on the microhardness of nanofilled resin-based composite restoration polymerized with high-intensity LED light curing units

In the present investigation, dissimilar materials such as electrolytic tough pitch copper, and aluminum 6061-T651 were welded by friction stir welding technology. Effects of tool tilt angle on the mechanical and metallurgical properties were studied experimentally for dissimilar material systems. In the present study, the tool tilt angle was varied from 0° to 4° with an interval of 1°, while the other parameters such as rotational speed, welding speed, tool pin offset, and workpiece material position were kept constant. Macrostructure analysis, tensile test, macro hardness measurement, scanning electron microscopy, and energy dispersive x-ray spectrographic tests were performed to evaluate the weld properties of dissimilar copper–aluminum joints. The results revealed that a defect free dissimilar copper–aluminum friction stir welding was achieved by tilt angles 2°, 3°, and 4°. The maximum tensile strength was reported to be 117 MPa and the macro hardness was reported to be 181 VH (in the nugget zone) at a tilt angle of 4°. The macro hardness was increased as the tilt angle increases from 0° to 4°. In addition to this, the thermo-mechanically affected zone (at the copper side) was found to be the weakest zone for a dissimilar copper–aluminum friction stir welding system.

Performance improvement of water in glass evacuated tube solar water heaters has received attention from many researchers yet the effect of geometric parameters on the performance of the system has not been fully explored. In this work, the effect of collector tube length, diameter and tilt angle on the temperature and velocity distribution was studied using computational fluid dynamics (CFD). The results of the CFD model were validated against experimental data. The collector tube length was found to have a significant influence on both the temperature in the storage tank and the velocity distribution. The longest collector tube (2000 mm) achieved the highest temperature compared to collector lengths of 1800 mm and 1600 mm. A larger collector tube diameter of 52 mm enhanced the average temperature in the storage tank compared to collector tube diameters of 42 mm and 47 mm. The effect of tilt angle on velocity distribution was analysed using tilt angles of 10, 23, 30, and 45 degrees and the results showed that the average flow velocity for lower tilt angles was high, however, the maximum flow velocity which occurs at regions close to the boundary between the collector tube and the storage tank was higher for high tilt angles.

Mixing fans typical of those used in naturally ventilated poultry housing in warm weather were tested in an experimental building to determine effects of fan placement height and tilt angle on airflow. The airflow pattern generated by tilted mixing fans can be characterized as the air jet from the fan impinging at an angle to the floor and forming a wall jet flowing along the floor. Tests with three fans showed that area-averaged and maximum air velocities near the floor varied strongly with fan height and tilt angle. For tilt angles of 20° or less from horizontal, area-averaged velocity increased with tilt angle and decreased with increasing fan height. Contour plots of velocity were generated for comparing airflow 25 cm (10 in.) above the floor. Combinations of fan, tilt, and height can be selected to achieve desirable area-averaged air velocities while minimizing areas covered with undesirably high air velocities.

PV (photovoltaic) panels are getting more attentive in our life due to its big advantages. At the same time its efficiency is an important factor to consider. At any location on the earth its output is affected by its tilt and azimuth angles. These angles play an important role in the efficiency of the photovoltaic panel. In this paper, the effect of tilt angle on PV performance determines. The PV module tilt angle changes from 0° to 90° using Arduino Mega 2560 to control it. The values of the PV panel output voltage collects using the Arduino and output power calculates at different tilt angles to know the effect of tilt angle shift on the PV panel output. A mathematical equation derives to calculate the effect of tilt angle on the PV output.

This paper analyzes the optimum orientation and tilt angle effects on photovoltaic (PV) module performance in Jeddah, Saudi Arabia. This analysis will begin with the description of solar radiation and tilt angle concepts. These concepts are then used to investigate the performance of PV modules by determining the power output while varying the tilt and azimuth angles. Several azimuth and tilt angles have been analyzed for monthly, bimonthly, trimonthly, quarterly, six-monthly, and yearly periods to determine how much power output can be generated and to select the best orientation angles for the PV system. The results indicate that the highest monthly average output power of the PV is 0.225 kW, obtained in June at the 0° tilt surface of the 1-kW PV panel. However, bimonthly, trimonthly, quarterly, six-monthly, and yearly adjustments result in lower power output, with yearly adjustment giving the lowest power. Therefore, the tilt angle should always be adjusted in the shortest time possible in the interest of achieving the maximum possible power output and improving the efficiency of the PV system.

Effect of tilt angle on the performance and electrical parameters of a PV module: Comparative indoor and outdoor experimental investigation

A Theoretical Model for Calculation of Formation Force D.L. Dai; D.L. Dai China University of Petroleum Search for other works by this author on: This Site Google Scholar Q.F. Pan; Q.F. Pan Greatwall Drilling Company of CNPC Search for other works by this author on: This Site Google Scholar D.L. Gao D.L. Gao China University of Petroleum Search for other works by this author on: This Site Google Scholar Paper presented at the Canadian International Petroleum Conference, Calgary, Alberta, June 2008. Paper Number: PETSOC-2008-001 https://doi.org/10.2118/2008-001 Published: June 17 2008 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Dai, D.L., Pan, Q.F., and D.L. Gao. "A Theoretical Model for Calculation of Formation Force." Paper presented at the Canadian International Petroleum Conference, Calgary, Alberta, June 2008. doi: https://doi.org/10.2118/2008-001 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsPetroleum Society of CanadaPETSOC Canadian International Petroleum Conference Search Advanced Search AbstractA theoretical model of formation force which derives from 3D rock-bit interaction model and weight on bit (WOB) is presented. Except for considering drilling trajectory changes and formation anisotropy, the model accounts for the effects of bit anisotropy and bit tilt angle which did not study in models published before. The effect of bit anisotropy and bit tilt angle on formation forces is discussed in detail. The analysis allows us to calculate formation forces more accurate in the trajectory controlling. The model is used to estimate the anisotropic drilling characteristics of the formation in Kelasu conformation which has high stratigraphic dip in Tarim Basin in western China. The result reveals that it can properly reflect the strata drifting characteristic of the formation being evaluated.IntroductionEstimation of the forces between the drill string and the formation is vital for planning drilling trajectory in directional well and for preventing deviation in straight hole. Many models for calculating formation force have been published [1–11]. Among these, models presented in literature [1–9] assume the bit equilibrium under constant inclination and azimuth angles. They do not consider the effect of bit anisotropy and bit tilt angle. However, in the drilling process, borehole inclination and azimuth may continuously change, and drilling bits are not isotropy. Models suggested by Yan and Yan et al [10, 11] can be used in the condition of inclination and azimuth changes. But they also do not consider the effect of bit anisotropy and bit tilt angle. Because of its anisotropy and tilt angle, a bit can not move on the direction of mechanical resultant force even if it penetrates an isotropy formation, which indicates that bit anisotropy and bit tilt angle have an effect on formation forces.Thus existing models can not predict formation forces with required accuracy. In this paper, a new model for calculating formation forces is presented. The presented model takes into account the effects of bit anisotropy, bit tilt angle and drilling trajectory changes on formation forces. The effects of bit anisotropy and bit tilt angle on formation forces are discussed.Formation anisotropy and bit anisotropyAnisotropy of the formation can be expressed by the formation anisotropy index. If an isotropic bit drills a hole in the orthogonal anisotropy formation, formation anisotropy index can be defined as [9]:Equations (available in full paper)Bit anisotropy expressed by bit anisotropy index is the ratio of drillability in lateral and axial direction of a bit. If an anisotropic bit makes footage in an isotropic formation, anisotropy index of the bit can be expressed by [9]:Equations (available in full paper)Formation force modelA Cartesian system of coordinates is selected with Zd axis opposite to the drilling direction (Fig.1). Then the side force at the bit can be obtained from the following equation:Equations (available in full paper) Keywords: calculation, inclination, azimuth, anisotropy index, tendency, isotropy formation, bit anisotropy, formation anisotropy index, drillstring design, reservoir characterization Subjects: Drillstring Design, Drilling Operations, Reservoir Characterization This content is only available via PDF. 2008. Petroleum Society of Canada You can access this article if you purchase or spend a download.

Effects of ambient temperatures, tilt angles, and orientations on hybrid photovoltaic/diesel systems under equatorial climates

Performance analysis of a solar-assisted ground source heat pump with a single vertical U-tube ground heat exchanger

A b s t r a c t: Taking into account the substantial cost of a photovoltaic (PV) system, should maximise module efficiency. The experimental tests are conducted with the group of 10 photovoltaic panels installed on the roof of the building of the Electrical Engineering Faculty resided on the Polytechnic University of Tirana. The PV panels are split in groups of two with 5 different tilt angles, respectively 0°, 30°, 45°, 60° and 90°. To view the pollution and the tilt angle effects, one of the panels is cleaned every day. Monitoring the group of panels gives interesting conclusion about the impact of the dust and the tilt angle on PV production efficiency, as well as, the impact of the tilt angle to the dust settlement. The results show an increase in the performance of clean panel. The I-V and P-V characteristics curves were constructed and compared. A b s t r a c t: Taking into account the substantial cost of a photovoltaic (PV) system, should maximise module efficiency. The experimental tests are conducted with the group of 10 photovoltaic panels installed on the roof of the building of the Electrical Engineering Faculty resided on the Polytechnic University of Tirana. The PV panels are split in groups of two with 5 different tilt angles, respectively 0°, 30°, 45°, 60° and 90°. To view the pollution and the tilt angle effects, one of the panels is cleaned every day. Monitoring the group of panels gives interesting conclusion about the impact of the dust and the tilt angle on PV production efficiency, as well as, the impact of the tilt angle to the dust settlement. The results show an increase in the performance of clean panel. The I-V and P-V characteristics curves were constructed and compared. Key words: photovoltaic module; dust; module performance; tilt angle; I-V characteristics REFERENCES : [1]Tian, W., Wang, Y., Ren, J., Zhu, L.: Effect of urban climate on building integrated photovoltaics performance. Energy Conversion and Management, vol. 48 (1), pp. 1–8, (2007). [2]Kaldellis, J. K., Kokala, A.: Quantifying the Decrease of the Photovoltaic Panels’ Energy Yield Due to Phenomena of Natural Air Pollution Disposal, Energy, vol. 35, pp. 4862–4869, (2010). [3]Betul Bektas Ekici: Variation of photovoltaic system performance due to climatic and geographical conditions in Turkey, Turk J Elec Eng & Comp Sci, Vol. 24, Num. 6, pp. 4693–4706 (2016). [4]SunPower Limited Product and Power Warranty for PV Modules, Sun Power®, July 2010. [5]Miqdam T. Chaichan, Bashar A. Mohammed, Hussein A. Kazem: Effect of pollution and cleaning on photovoltaic performance based on experimental study, International Journal of Scientific & Engineering Research, Vol. 6, Issue 4, pp. 594–601 (2015). [6]Cano, J.: Photovoltaic Modules: Effect of Tilt Angle on Soiling, Master thesis, Arizona State University: August 2011. [7]AlAiawy, I. T.: Wind and other factor requrements to solar energy applications in Iraq, Solar and Wind Technology, vol. 7, pp. 597–600 (1990). [8]Mani, M. and Pillai, R.: Impact of dust on solar photo-voltaic (PV) performance: Research status, challenges and recommendations, Renewable Sustainable Energy Rev., vol. 14, pp. 3124–3131 (2010). [9]John, J. J.: Characterization of Soiling Loss on Photo-voltaic Modules, and Development of a Novel Cleaning System, Ph.D. Thesis, Department of Electrical Engineering, Indian Institute of Technology Bombay, 2015 [10]www.geo.edu.al/site/, Institute of GeoSciences, Energy, Water and Enviroment, 2015. [11]Laudani, A., Fulginei, F. R., Salvini, A.: Identification of the one-diode model for photovoltaic modules from datasheet values. Sol Energy, vol 108, pp. 432–446 (2014). [12]Guide to Interpreting I-V Curve Measurements of PV Arrays, Solmetric Corporation, 2010. [12]Pantic, Lana S., Pavlovic, Tomislav M.: Determination of physical characteristics of horizontally positioned solar module in real climate conditions in Nis, Serbia, Physics, Chemistry and Technology, vol. 14, No 1, pp. 37–51 (2016).

Measurements of downwelling shortwave (SW) and longwave (LW) irradiance were carried out on an oceanographic buoy close to the island of Lampedusa (Italy), in the central Mediterranean Sea. Irradiance measurements on the buoy were acquired at high time resolution together with the radiometer pitch and roll angles. The measurements carried out during 2016 have been compared with ground-based observations made at the Lampedusa Atmospheric Observatory, about 15 km northeast of the buoy. The radiometers were compared before and after deployment on the buoy and are traceable to the World Radiometric Reference scale. The SW measurements were corrected for the thermal offset. A small bias (measurements over the sea are smaller than on land) of about −2 W m−2 is found in the daily mean SW, and a moderate bias of +6.2 W m−2 (irradiance over the sea is larger than on land) is found in the LW. Similar biases are found when instantaneous measurements obtained with horizontal radiometers, clean domes, and cloud-free conditions are selected, suggesting that impacts of the moving platform and poor dome cleaning are minor at this site. The effect of the mean tilt angle was also investigated. Deviations in the hourly mean SW irradiance are on the order of 20% for a mean offset of 4° with respect to the solar zenith angle; the effect of tilt angle on LW irradiance appears to be negligible. Radiative transfer calculations show that the observed biases may be ascribed to the differences in the instrument altitude (through radiation absorption, scattering, and emission by the atmospheric constituents in the lowest atmospheric layers) and in the SW surface albedo.