This study aims to assess the effect of adding twisted fins in a triple-tube heat exchanger used for latent heat storage compared with using straight fins and no fins. In the proposed heat exchanger, phase change material (PCM) is placed between the middle annulus while hot water is passed in the inner tube and outer annulus in a counter-current direction, as a superior method to melt the PCM and store the thermal energy. The behavior of the system was assessed regarding the liquid fraction and temperature distributions as well as charging time and energy storage rate. The results indicate the advantages of adding twisted fins compared with those of using straight fins. The effect of several twisted fins was also studied to discover its effectiveness on the melting rate. The results demonstrate that deployment of four twisted fins reduced the melting time by 18% compared with using the same number of straight fins, and 25% compared with the no-fins case considering a similar PCM mass. Moreover, the melting time for the case of using four straight fins was 8.3% lower than that compared with the no-fins case. By raising the fins’ number from two to four and six, the heat storage rate rose 14.2% and 25.4%, respectively. This study presents the effects of novel configurations of fins in PCM-based thermal energy storage to deliver innovative products toward commercialization, which can be manufactured with additive manufacturing.
In this paper, first and second order sliding mode controllers are designed for a single link robotic arm actuated by two Pneumatic Artificial Muscles (PAMs). A new mathematical model for the arm has been developed based on the model of large scale pneumatic muscle actuator model. Uncertainty in parameters has been presented and tested for the two controllers. The simulation results of the second-order sliding mode controller proves to have a low tracking error and chattering effect as compared to the first order one. The verification has been done by using MATLAB and Simulink software.
Position control of servo motor systems is a challenging task because of inevitable factors such as uncertainties, nonlinearities, parametric variations, and external perturbations. In this article, to alleviate the above issues, a practical adaptive fast terminal sliding mode control (PAFTSMC) is proposed for better tracking performance of the servo motor system by using a state observer and bidirectional adaptive law. First, a smooth-tangent-hyperbolic-function-based practical fast terminal sliding mode control (PFTSM) surface is designed to ensure not only fast finite time tracking error convergence but also chattering reduction. Second, the PAFTSMC is proposed for the servo motor, in which a two-way adaptive law is designed to further s
... Show MoreBackground: acrylic resin denture base consider a common denture base material for its acceptable cost, aesthetic and easy processing but still has disadvantages including easy of fracture and low impact strength. Material and method: The experimental group was prepared by addition of 15% phosphoric acid 2-hydroxyethyl methacrylate ester (PA2HEME) with polymethyl methacrylate monomer; the experimental groups was compared with the control one. The specimens were prepared according to ADA specification No. 12 with dimension 65 mm x 10 mm x2.5 mm (length x width x thickness respectively). The prepared specimens were tested by three-point flexural strength utilizing Instron Universal Testing Machine (WDW, Layree Technology Co.), Shore D hard
... Show MoreBackground: The daily cleaning routine of the silicone maxillofacial prostheses by the patient may cause some alteration in the materials properties. The purpose of the present study was to investigate the effect of different disinfection procedures on some properties of silicon dioxide reinforced Cosmesil M511 HTV maxillofacial silicone. Materials and Methods: One hundred and sixty (160) specimens were prepared by mixing 5% SiO2 nano particles and 0.5% intrinsic cream color into the silicone polymer according to manufacturer's instructions. Specimens were divided into 4 groups according to the performed test (tear strength, surface hardness, surface roughness and color) with 40 specimens each. Each group was further subdivided according to
... Show MorePraise be to the one who taught the pen. Without the pen, the knowledge of the first two would not have reached the others. Then, praise the one who taught man from the printing industry unless he knew, and prayers and peace be upon those who guide all nations to the invention and the follower in the matter of religion, and to his family and companions.
The use of Qur’anic use is an integrated and important topic that examines the building and the meaning, which are two major titles in the study of Arabic, so the goal of scholars when going into these explanations was to find out the wonderful linguistic miracle of this great book.
Scholars have worked hard to talk
The research study of the possibility of the application of the quality management system under the international standard ISO ISO9001: 2008 in the station project Rustumiya wastewater treatment of the Department of SEWER BAGHDAD - Baghdad MOREALITY as the first step in the right direction towards the implementation of total quality management (TQM), and the research Find the gap between the international standard and the quality system used in the organization surveyed through the use of checklists to analyze the gap, the checklist have included (191) items distributed on five basic requirements, according to the appearance in the international standard, namely, (quality management system, management responsibility, resource man
... Show MoreThe present work aimed to make a comparative investigation between three different ionospheric models: IRI-2020, ASAPS and VOACAP. The purpose of the comparative study is to investigate the compatibility of predicting the Maximum Usable Frequency parameter (MUF) over mid-latitude region during the severe geomagnetic storm on 17 March 2015. Three stations distributed in the mid-latitudes were selected for study; these are (Athens (23.50o E, 38.00o N), Jeju (124.53o E, 33.6o N) and Pt. Arguello (239.50o W, 34.80o N). The daily MUF outcomes were calculated using the tested models for the three adopted sites, for a span of five-day (the day of the event and two days preceding and following the event day). The calculated datasets were co
... Show Morestudy aims to examine education and the challenges of globalization in light of Corona pandemic. The examination involves surveying a randomly selected sample from the University of Baghdad’s professors, particularly from the colleges of Education for Women, Arts, and Sciences. The purpose of this examination is to learn about the dimensions of globalization, its effects on the educational process, and the importance of distance education during the spread of Corona virus quarantine. To achieve this, the researcher followed a descriptive and analytical approach by applying a questionnaire to a sample of 70 teachers who were randomly selected electronically. Results have shown that 78.6% emphasized the contribution of globalization duri
... Show MoreIraq suffers from serious pollution with harmful particles that have important direct and indirect effects on human activities and human health. In this research, a system for detecting pollutants in the air was designed and manufactured using infrared laser technology. This system was used to detect the presence of pollutants in the dust storms that swept the city of Baghdad which could have a negative impact on human health and living organisms.
The designed detection system based on the use of infrared laser (IR) with a wavelength of 1064 nm was used for the purposes of detecting pollutants based on the scattering of the laser beam from these pollutants. The system was aligned to obtain the best signal for the scattered rays, w
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