Angle Of 45o Research Articles

Effects of Bending and Re-bending on Mechanical Properties of Locally-Manufactured Steel Rebars

Steel rebars experience deformation when subjected to bending and re-bending operations. Subsequently, their microstructures are impaired thus affecting the mechanical properties and leading to failure. This study establishes the effects of bending and re-bending the steel rebars on the mechanical properties. Experiments were conducted to determine the effects of bending and re-bending of the steel rebars. Testing was conducted on Ten virgin and Thirty specimens which were bent and re-bent at 45º, 90º, and 180º, and followed by tensile tests. Yield strength, ultimate tensile strength, elongation, and ultimate tensile strength to yield strength ratio (Rm/Re), were recorded. Results showed the yield strength, ultimate tensile strength, elongation, and Rm/Re of virgin steel rebars varied from 553.62 MPa to 618.49 MPa, 634.39 MPa to 745.68 MPa, 17.6 % to 21.67 %, and 1.14 to 1.19. The yield strength, ultimate tensile strength, elongation, and Rm / Re of bent and re-bent steel rebars at angles of 45º, 90º, and 180º varied from 603.67 MPa to 677.38 MPa, 692.82 MPa to 751.76 MPa, 6.88 % to 19 % and 1.09 to 1.21. It was established that bending and re-bending increase strength and reduce the ductility of the rebars proportionally.

Design of a Circular Micro-strip Patch Antenna for Improved Directivity and Gain of Mobile Communication Base Station

This study presents the design of Circular Micro-strip Patch Antenna (CMPA) for improved directivity and gain of mobile communication base station. The design incorporates a Rogger/5880 substrate material with a permittivity of 2.2, tangent angle of 0.00009 and a substrate height (thickness) of 0.98μm at a frequency of 1.65THz. Diversity Antenna Array Processing (DAAP) and Chebyshev Antenna Array (CAA) methods were used in the design. AutoCAD software and 2D data plotter were used for the diagrams and charts while Maple software was used for simulation. For angles of 0o, 30o, 60o, 90o, 120o, 150o and 180o, the array factors are 7.84dB, 7.85dB, 7.87dB, 7.88dB, 7.87dB, 7.85dB and 7.84db respectively. The results from the design demonstrated a remarkably low side lobe level of 0.01dB, indicating excellent suppression of unwanted radiation in undesired directions. Additionally, the antenna exhibits a Voltage Standing Wave Ratio (VSWR) of unity, ensuring maximum power transfer efficiency from the source to the load. Furthermore, the antenna shows a high directivity and gain of approximately 9dB, which enhances the signal strength and coverage range. The Half Power Beam-width (HPBW) and First Null Beam-width (FNBW) was measured as 300 and 600 respectively. These parameters depict the angular width of the main radiation beam and the sharpness of the beam pattern’s nulls. In all, the designed CMPA with its CAA based antenna array holds great potential for communication networks and for mobile communication base station, offering enhanced performance in terms of radiation characteristics and signal quality.

Numerical simulation of heat pipe solar system combined with finned thermal storage unit incorporating mixture of nanoparticles and paraffin

The core aim of this investigation is to simulate the melting of paraffin within a solar heat pipe unit combined with thermal storage unit, while taking into account the presence of metallic fins. To enhance system performance, Multi-Walled Carbon Nanotube (MWCNT) nanoparticles were blended into the paraffin material (RT82) using a homogeneous mixture approximation. The temperatures of the heat pipe and inner walls were derived from previous experimental research. Three distinct fin arrangements were utilized, and simulations were carried out employing numerical method. Validation procedures were undertaken to verify the accuracy of the modeling and the applied approximations, relying on both prior experimental data and numerical publications. The investigation presents data on the liquid fraction (LF), temperature (T), and stream function for diverse configurations. This holistic approach seeks to deepen comprehension of the interactions among these elements within a solar collector system, offering vital insights for performance optimization. The outcomes demonstrated a notable improvement in LF, increasing by roughly 15.15% at t = 1200s with the integration of MWCNT. Furthermore, with the passage of time from 400 s to 1200s, the incorporation of additives results in a notable rise in LF and T, demonstrating enhancements of approximately 97.74% and 130.8% correspondingly. Notably, the utilization of fins positioned at a 90o angle expedites the melting process, yielding a 38.24% LF increase compared to the base case at t = 1200s. Moreover, the impact of fins demonstrates a 3.32% increase over time. In essence, these results emphasize the effectiveness of incorporating MWCNTs and fine-tuning fin configurations to accelerate the melting process, offering valuable insights for the progress of solar thermal systems.

Midwives' approach to the prevention and repair of obstetric perineal trauma in Spain.

Different clinical practice guidelines include recommendations on how to prevent and repair obstetric perineal trauma, as well as the use of episiotomy. To evaluate the variability in midwives' professional practices for preventing and repairing perineal trauma, as well as the professional factors that may be associated with the restrictive use of episiotomy. Observational cross-sectional study. Three hundred five midwives completed an anonymous questionnaire developed by the authors and distributed across various midwifery scientific societies. The main outcomes measured were the frequencies of adopting specific practices related to perineal injury prevention and repair, episiotomy technique and restrictive episiotomy use (<10%). Odds ratios (OR) and adjusted odds ratios (aOR) with 95% confidence intervals were estimated. Intrapartum perineal massage was not normally used by 253 (83%) of midwives, and 186 (61%) applied compresses soaked in warm water to the perineum. Regarding episiotomy, there was a great deal of variability, noting that 129 (42.3%) adopted a restrictive use of this procedure, 125 (41%) performed it between 10% and 20%, while 51 midwives (16.7%) performed it in more than 20% of cases. In addition, 165 (54.1%) midwives followed an incision angle of 60º. Concerning tears, 155 (50.8%) usually sutured first-degree tears and 273 (89.5%) always sutured second-degree tears. Midwives attending home births (aOR = 6.5; 95% CI: 2.69-15.69), working at a teaching hospital (aOR = 3.69; 95% CI: 1.39-9.84), and the ones who recently completed their professional training (aOR = 3.58; 95% CI: 1.46-8.79) were significantly more likely to adopt a restrictive use of episiotomy. There is a significant variability in Spanish midwives' practices for preventing and repairing perineal tears. Moreover, the restrictive use of episiotomy is associated with midwives attending home births, working in teaching hospitals and having recent professional training. No patient or public contribution.

THE EFFECT OF THE ANGLE AND DIMENSIONS OF A CROSS-SECTION SPECIMEN ON THE TORSIONAL STRENGTH OF AISI 1020 SQUARE STEEL SHAFT

The unknown torsional strength due to the inconsistency of the angles and dimensions of the square cross-section of AISI 1020 steel specimens in the torsion test is the problem encountered. The research method included: preparation of square AISI 1020 steel specimens measuring 6 mm x 6 mm x 160 mm, measurement of 2 diagonal angles of the cross section of the specimen and dimensions of the cross section at 5 observation points along the specimen receiving torsion loads, torsion testing of specimens, analysis of torsion test results data, and drawing conclusions. The results of the study affect the angle and dimensions of the specimen cross-section on the torsional strength of the AISI 1020 steel square shaft which has a greater value at the angles of 89o and 91o than 90o which with an angle of 89o at dimensions of 5.96 mm x 5.96 mm has a torsional strength of 412 MPa, while at an angle of 90o with dimensions of 5.96 mm x 5.96 mm it has a torsional strength of 359 MPa, and for an angle of 91o in dimensions of 5.95 mm x 5.95 mm has a torsional strength of 402 MPa. The average torsional strength is achieved in the range of 351 to 397 MPa, at an angle of 89o the torsional strength increases by 46 MPa or around 13.1 %, and at an angle of 91o the torsional strength increases by 43 MPa or around 12.3%.

Prediction of geomechanical changes in faulted rock mass around underground structures subjected to earthquakes

Faults are a type of geological structure that often leads to geological disasters in underground structures under normal conditions and especially when earthquakes occur, thereby requiring careful study.This article introduces some numerical simulation results on the seismic wave propagation process, on changes in stress and displacement states in the rock mass with a small fault of a dip angle of 45o, around a circular cross-section tunnel, using the discrete element method (Universal distinct element Code - UDEC). Three cases are simulated: a) The tunnel is located in the hanging wall rock, the fault is located 10m from the centre of the tunnel on the vertical axis; b) The fault runs through the centre of the tunnel and c) The tunnel is located in the footing wall rock, the fault is located 10m from the centre of the tunnel on the vertical axis. The results obtained show a very clear influence of the position and location of the fault on the geomechanical changes in the rock mass around the tunnel, contributing to the reasonable design of tunnels subjected to earthquakes.

Novel Polyimide-Based Conformal Bandpass FSS for X-band RADAR Communications

A linearly polarized wide bandpass frequency selective surface (FSS) for RADAR communication application has been presented. The proposed FSS is constructed in a single layer with a size of 0.25 λ0. This FSS utilizes a rhombus slot comprised of a head slot and a meander line to provide a single-wideband resonance. The proposed FSS operates in the X-band communication frequency range from 7.98 to 12.1 GHz (4.12 GHz) and achieves a minimum insertion loss of 0.1 dB, respectively. The designed FSS is developed on a flexible substrate with a low profile of 0.05 mm. The FSS exhibits stable angular performance in the scope of incidence angle of 60º for both TE and TM modes. An equivalent circuit model is designed to depict the desired frequency response. Furthermore, a bending analysis has been carried out to verify the conformal nature of the proposed unit cell. The prototype is fabricated and the performances are validated with experimental results.

Computational Analysis Of Pipe Bend Angle Effect On Pressure Drop

The air conditioning system is a significant energy source inskyscrapersfor supplying cool air to all rooms. However, the process has energy losses due to the ducting used. If the problem of energy loss can be solved, the air conditioning system will bring advantages in terms of energy efficiency and financial savings. A pressure drop in air duct pipe installations, such as pipe bends, is one type of energy loss. This research intends to use Computational Fluid Dynamics (CFD) to investigate the effect of pipe bend angles and velocity relationships on pressure drop in air duct pipe installations, which has previously been validated by experimental research with a 0.17% error percentage. This study focuses on square pipe bends with varying 45o, 60o, and 90o bend angles. The research showed that when testing the highest fluid velocity of 19.68 m/s, the highest pressure drop was 275.69 Pa on the pipe bend angle of 90o, while the lowest pressure drop was 256.41 Pa on the pipe bend angle of 45o. When testing the lowest fluid velocity of 9.77 m/s the highest pressure drop was 67.73 Pa on the pipe bending angle of 90owhile the lowest pressure drop was 62.98 Pa on thepipe bending angle of 45o. The simulation results indicate that the larger pipe bend angle result in a higherpressure drop, and vice versa.

Measurement and Risk Analysis of Ozone (O3) Concentrations in the 9 MeV and 12 MeV Electron Mode LINAC

This study investigates potential non-radiation hazards, specifically Ozone (O3) production, during Linear Accelerator (LINAC) electron mode radiotherapy. The research uses experimental measurements to determine Ozone concentration in the LINAC patient waiting room and control room. Measurements are taken assuming a ±2-hour delay in one working day, using 9 MeV and 12 MeV energy, 400 MU dose rate, and illumination angles of 0o, 90o, and 270o. Maximum Ozone concentrations in the LINAC patient waiting room and control room are found to be 6.6 ppb (12 MeV) and 8.3 ppb (12 MeV), respectively. These concentrations fall below the chemical threshold limit and are deemed safe for human exposure. Notably, potentially detectable Ozone levels are observed in the LINAC banker. Overall, this research highlights the importance of monitoring Ozone levels to ensure the safety of both patients and personnel in LINAC facilities.

Thermo-Fluidic Analysis of Pulsating Heat Pipes Charged with Water-Based Immiscible Fluid Pairs

Immiscible fluids may provide operational flexibility for pulsating heat pipes (PHPs) due to thermo-hydrodynamic diversity lead by each pure component. In this regard, present paper focuses on the thermo-fluidic analysis of non-uniform pulsating heat pipes charged with water-based immiscible fluid pairs. Research parameters cover gravity effect via the inclination angles (IA) of 0o and 90o, and fluid pair effect via two different water-based immiscible binary fluids as Water (W) – Hexane (H), and Water (W) – Pentane (P). The volumetric mixing ratios are W:H=1:1, 1:4, 4:1, 1:0, 0:1, and W:P=1:1, 1:4, 4:1, 1:0, 0:1; and the non-uniform flat plate type pulsating heat pipe (FP-CLPHP) has alternating-sequence parallel channels. The experiments are performed at the filling ratio of 40% (FR=40%), and flow phenomena is visualized. As some conclusions; at vertical orientation, the FP-CLPHPs having binary fluids of water-pentane show better thermal performance compared to the pure counterparts. Especially, the heat transfer characteristics of W:P=1:1 are the best ones among all the pure and binary fluids. On the other hand, as a conclusion of combination of non-uniform design and suitable thermophysical properties, the FP-CLPHPs charged with pure pentane, pure hexane or binary fluid of W:P=1:4 can work independent from gravitational force.

ANALISA KEBUTUHAN LAHAN PARKIR PASAR PURI PATI

Puri Market, which is located on Jalan Colonel Sunandar, precisely in the center of Pati Regency, is a traditional market which is the basis for the people of Pati to sell and buy all life-sustaining needs. This needs to be taken into account considering that the existence of an activity center must have as few parking areas as possible. Therefore, this study was carried out with the aim of providing recommendations for parking characteristics, parking space capacity and planning the most optimal parking layout for Puri Pati Market. Conditions are reviewed on 1 weekend and 3 weekdays. Namely Sunday, Monday, Wednesday and Thursday. From 06.00 to 12.00. The data used in this research are primary data and secondary data. The results of the research are that the characteristics of motorbike parking spaces for the Puri Pati Market area are 345 SRP which is in accordance with the 1996 Directorate General of Land Transportation standards. At Puri Pati Market There are also no entrances and exits that use electronic parking. With the existing motorbike parking space capacity of 280 SRP at Puri Pati Market, it can still meet existing parking needs. From the calculations that have been carried out, it is known that the need for motorbike parking space at Puri Pati Market is 345 SRP. In planning the parking layout using a 90º angle in the motorbike and car parking area as planned, namely being able to accommodate 280 motorbikes and 100 cars. With a comparison using an angle of 60º, we get only 152 motorbikes and 80 cars per plot.

Effects of Differences in Epidural Needle Entry Point and Angle of Rotation of Needle Hub on the Onset and Duration of Sensory Blockade in Lower Limb Orthopaedic Surgeries: A Randomised Controlled Trial

Introduction: Epidural anaesthesia is a boon for providing prolonged analgesia for postoperative pain relief. The influence of epidural needle insertion on the onset of the block, which has not been studied previously, is significant. Aim: To analyse the effect of epidural needle entry and rotation of the needle on the onset and duration of the block. Materials and Methods: This double-blinded randomised controlled trial was conducted at the Department of Anaesthesiology, SRM Institute of Science and Technology, Chennai, Tamil Nadu, India from March 2020 to August 2021 on 70 patients undergoing leg and ankle surgeries. They were randomised into Group-ML (midline approach) and Group-PM (paramedian approach). In Group-ML, midline epidural needle entry was followed by catheter insertion. In Group-PM, the needle entry was paramedian, and the bevel was turned 45º towards the surgical site for catheter insertion. A 10 mL of 0.5% bupivacaine was administered. Postoperatively, epidural infusion was initiated using 0.125% bupivacaine with 2 μg/mL fentanyl. The time taken for catheter placement, onset of motor and sensory blockade, maximum sensory level attained, duration of sensory blockade, consumption of local anaesthetics, haemodynamic profile, and the need for rescue analgesia were monitored. Continuous data were analysed using the Student's t-test, and categorical data were analysed using the Chi-squared test with International Business Machines (IBM) statistical product and service solutions software version 27.0 Results: Both groups were comparable with respect to demographics. The mean age in Group-ML was 40.9±25.93 years, while in Group-PM it was 41.028±20.576 years, with a p-value of 0.981. The mean BMI in Group-ML was 24.91±2.998 kg/m2 , while in Group-PM it was 24.96±2.527 kg/m2 , which was statistically insignificant with a p-value of 0.944. A total of 21 males in Group-ML and 28 males in Group-PM participated in the study; the distribution was found to be statistically insignificant with a p-value of 0.067. The time taken for the placement of the epidural catheter was around 288 seconds in Group-ML and 322 seconds in Group-PM, with a p-value of 0.0035. The onset of sensory block was around 17 minutes in Group-ML and 13 minutes in Group-PM, respectively, with a p-value of 0.0001. The duration of sensory block or the time taken for two-segment regression of level was around 102 minutes and 128 minutes in Group-ML and Group-PM, respectively (p-value 0.0001). The rescue analgesic was required in seven patients of Group-ML and none in Group-PM, with a p-value of 0.005. The haemodynamic profile intra and postoperatively and postoperative VAS score were statistically insignificant between the groups. Conclusion: The paramedian approach and epidural catheter insertion with the needle rotated at an angle of 45º towards the surgical side provide a rapid onset of the sensory and motor block with extended duration of the sensory blockade and reduced consumption of local anaesthetics.

Vertical Axis Wind Turbine for Low Wind Speed Environment: Effect of Scoop Harmony Blade

The wind condition in Malaysia is in the low-speed category with an average speed of 1 ms-1 to 4 ms-1. Effect of ground level relies significantly on the wind speed distribution. Despite these conditions, it is less suitable for the development of horizontal wind turbine as an energy source. The obvious weakness is the lack ability to self-start and predict the wind direction thus affects the energy efficiency output. To overcome this problem, improvement of the vertical axis wind turbine design is observed to be the solution in replacing horizontal axis wind turbine. Hence, this study is to investigate a suitable type of vertical axis wind turbine blade design for the best performance RPM output in a low-speed wind environment. The investigation was conducted in a Longwin LW-9300R subsonic wind tunnel at 0 ms-1 to 10 ms-1 wind speed condition from three wind turbine blades specified as Solid Harmony, Scoop Harmony and Conventional Savonius blade with angle of 90º, 135º and 180º to determine the highest RPM productivity. Result shows that Scoop Harmony blade delivers the highest RPM blade output while Savonius 180º is seen to have the highest self-start blade achieved at 64 rpm at 1 ms-1 wind speed. However, Solid Harmony shows an acceptable range TSR of 0.5 with difference of 23% lower than Scoop Harmony. This shows that both Scoop Harmony has a higher performance RPM but Solid Harmony still has the potential design to be applied at low-speed condition due to its low TSR output.

Effects of an Inclined Cente red Conductor on MHD Natural and Forced Convection Within a Heated Wavy Chamber

The study of the effect of hall and ion slip on an inclined conductor on MHD natural and forced convection in a heated wavy chamber with a constant transversal magnetic field applied. The governing momentum and energy equation were solved by applying finite central scheme approximation and the resulting partial difference equations were solved by MATLAB software. The study showed that an increase heat absorption coefficient lowers the surface heat transfer thus lowering flow rate. An increase in Rayleigh number increases the flow rate while an increase in the angle of inclination of the conductor increases the buoyancy force component thereby increasing the flow rate. The results further showed that flow rate became higher at an inclination angle of 90º. In addition, the results also showed that an increase in Hartmann increases the flow rate. The Hartmann number, Rayleigh number and Absorption coefficient are analytically discussed and represented in tables and graphical profiles with respect to flow velocity and temperature profile due to engineering demand. This current study a direct application in the development of MHD propelled vessels in the marine and space-craft department.

EDM Electrode Design and Analysis to Enhance Process Performance

Electric discharge machining (EDM) is regarded as one of the most energy-efficient manufacturing processes for exceptionally accurate processing of any electrically conductive material, regardless of mechanical properties. EDM is a non-contact process utilized in various industries, including aerospace, industrial, instruments, molds, dies, and medical tools; also, it is beneficial for hard materials with simple or proficient geometries and shapes. Although EDM is for machining "difficult to machine" metals, such as those used in the mold and die industries, metal properties indicate potential capability in the domain of surface modification due to the electrical spark between the tool and the work material. This paper investigates the machining of Alloy steel X210 by using the most affecting parameters and how electrode angles contribute to responses, as MRR, Electrode wear ratio, and surface finish, which the manufacturing industry uses to make die tools, molds, automotive parts, and other products. Electrodes with angles of 0o and 90o are used to machine workpieces using WEDM (dk7740). Electrode Angle, peak discharge current, pulse-on time, and pulse-off time were controllable parameters in this study. While all other criteria are constant, variables have been studied. The effects of the four aspects on the four variables were statistically analyzed using ANOVA by MINITAB. Regression models for the responses were developed. Regression mathematical models have been developed for Alloy steel X210 workpieces to increase productivity and industry results.

Effect of fill pattern on flexural performance of FDM printed PLA

ABSTRACT In most biomedical devices, such as fracture fixation devices and medical tools, the printed part is subjected to complex loadings that involve large deflections instead of large strains. Among various FDM tool path parameters, the fill pattern has a critical role in controlling voids and raster bonding. This work highlights the flexural performance of the PLA-printed part based on various fill patterns, such as concentric, linear, Hilbert, raster angle 45º, alternate pattern (0º/45º), and concentric pattern with holes resembling bone plate. Based on deposition paths, the dimensional changes and interlayer adhesion were analyzed before and after annealing. The flexural performance was evaluated using quasi-static three-point and four-point bend tests and dynamic flexural tests under temperature sweep. The annealed samples exhibit improved flexural strength regardless of infill pattern and loading conditions, with the concentric pattern showing better performance in both static and dynamic tests.

Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water-Etching and Transfer Process

HighlightsThe (001)-oriented ferromagnetic La0.67Sr0.33MnO3 films are stuck onto the (011)-oriented ferroelectric single-crystal 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 substrate with 0° and 45° twist angle.By applying a 7.2 kV cm−1 electric field, the coexistence of uniaxial and fourfold in-plane magnetic anisotropy is observed in 45° Sample, while a typical uniaxial anisotropy is found in 0° Sample.Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain engineering. In recent years, lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal orientations. Moreover, twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures. A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process, which could provide some insight in to the physical phenomena. In this work, the La0.67Sr0.33MnO3 (001)/0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (011) (LSMO/PMN-PT) heterostructures with 45º and 0º twist angles were assembled via water-etching and transfer process. The transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO < 110 >. A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO [110] easy axis is observed for the 45° Sample by applying a 7.2 kV cm−1 electrical field, significantly different from a uniaxial anisotropy with LSMO [100] easy axis for the 0° Sample. The fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45° twist angle causes different lattice distortion of LSMO, thereby enhancing both the fourfold and uniaxial anisotropy. This work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.

Optimization, formation, and evolution of the photoinduced curing gradients and in-situ lamellar gaps in additive manufacturing of ZrO2 ceramics: From curing to sintering behaviors

The photoinduced curing gradients and in-situ lamellar gaps were related to the three-dimensional curing mechanism of stereolithography and researched in this work. Based on the photocuring mathematic theories presented by our team, photoinduced curing gradients were influenced by printing parameters such as laser power and frequency, scanning angle, and printing thickness. Among these curing gradients, the inadequate curing area was the main factor affecting the surface quality and physical properties of ceramics. The in-situ lamellar gaps were derived from the inadequate curing area. The lamellar gap size of green bodies was enlarged in brown bodies (sintering at 1170 ℃) and shrunk in sintered bodies (sintering at 1500 ℃). The correlations between the surface quality and printing parameters were clarified by establishing mathematical formulations of the lamellar gap size. Furthermore, anisotropic volume shrinkage, anisotropic surface topography, and density and hardness evolutions were associated with the wrapped particle density differences induced by the photoinduced curing gradients. Finally, the optimal printing parameters (75% of laser power, laser frequency of 150 kHz, scanning angle of 90º, printing thickness of 25 μm, and scanning speed of 2.5 m/s) were obtained by the orthogonal experimental analysis. This study provides a distinct understanding of the high-quality forming and extreme-performance manufacturing of stereolithography.

Experimental Investigation into Natural Convection Heat Transfer inside Triangular Enclosure with Internal Hot Cylinder

Natural convection air heat transfer and fluid movement currents around a hot circular cylinder inside an inclined triangular enclosure has been analyzed experimentally. Three different sizes of an enclosure with a long side of 20, 25, and 30 cm, the thickness of 1 mm, and depth of 50 cm were used in the present work to give three radius ratios. The effect of Rayleigh number, radius ratio, the rotation angle of triangle enclosure, and the inclination angle of the apparatus with horizontal axis ? on the heat transfer process was investigated. The ranges of these parameters were: Rayleigh number from 5×106 to 2.5×108, radius ratio (0.345, 0.455, and 0.618), rotation angle (0o, 45o, and 90o), and inclination angle (0o, 45o and 90o). The results show that the heat transfer rates increase with increase in Rayleigh number and as the rotation angle of enclosure is changed from 0o to 90o. Moreover, the heat transfer rate increases linearly with Rayleigh number at higher radius at rotation angle 0o, 90o only. While, it increases slightly with Rayleigh number at rotation angle 45o. Additionally, the higher heat transfer rates occur at vertical position of enclosure inclination angle 90o and rotation angle 0o (the base of triangle at the bottom) and it decreases as inclination angle deviates from 90o to 0o. This behavior is reverse completely at higher radius ratio 0.618. Empirical correlations for the average Nusselt number has been found to depend on Rayleigh number., radius ratio, rotation angle and inclination angle.

DETERMINING THE OPTIMUM PARKING ANGLES FOR VARIOUS RECTANGULAR-SHAPED PARKING AREAS: A PARTICLE SWARM OPTIMIZATION-BASED MODEL

Reducing financial costs as much as possible through the effective and efficient use of parking areas is an important issue for sustainable urban planning. This can be achieved by optimizing the placement of angles of parking-lots. In this study, to determine the optimum parking angles for rectangular-shaped parking areas, a Particle Swarm Optimization-based model that aims to maximize the capacity of parking areas is developed. In the scope of the study, firstly, 324 parking area scenarios which have different dimensions from each other are created for testing the effectiveness of the model developed. Each scenario is separately analyzed by considering the optimization-based model and fixed-parking angles (0o, 30o, 45o, 60o and 90o) used in parking area planning. In the last step, parking area capacities obtained by applying different parking angles for each scenario and the total parking capacities for all scenarios are compared in detail. Results show that the capacities of parking areas can be increased up to approximately 50% with the model created. Besides, in contrast to existing literature, the findings of this study have proven that the optimum parking angle directly depends on the topology of the land. The model developed can be applied to all rectangular-shaped parking areas to achieve better urban planning.