Heat Transfer Enhancement of the Absorber Tube in a Parabolic Trough Solar Collector through the Insertion of Novel Cylindrical Turbulators

This study includes an experimental and numerical analysis of the performances of a parabolic trough collector(PTC)with and without cylindrical turbulators.The PTC is designed with dimensions of 2.00 m in length and 1.00 m in width.The related reflector is made of lined sheets of aluminum,and the tubes are made of stainless steel used for the absorption of heat.They have an outer diameter of 0.051 m and a wall thickness of 0.002 m.Water,used as a heat transfer fluid(HTF),flows through the absorber tube at a mass flow rate of 0.7 kg/s.The dimensions of cylindrical turbulators are 0.04 m in length and 0.047 m in diameter.Simulations are performed using the ANSYS Fluent 2020 R2 software.The PTC performance is evaluated by comparing the experimental and numerical outcomes,namely,the outlet temperature,useful heat,and thermal efficiency for a modified tube(MT)(tube with novel cylindrical turbulators)and a plain tube(PT)(tube without novel cylindrical turbulators).According to the results,the experimental outlet temperatures recorded 63.2°C and 50.5°C for the MT and PT,respectively.The heat gain reaches 1137.5 Win the MT and 685.8 Win the PT.Compared to the PT collector,the PTC exhibited a(1.64 times)higher efficiency.

Application of computational fluid dynamics in design of viscous dampers-CFD modeling and full-scale dynamic testing

Computational fluid dynamics(CFD)provides a powerful tool for investigating complicated fluid flows.This paper aims to study the applicability of CFD in the preliminary design of linear and nonlinear fluid viscous dampers.Two fluid viscous dampers were designed based on CFD models.The first device was a linear viscous damper with straight orifices.The second was a nonlinear viscous damper containing a one-way pressure-responsive valve inside its orifices.Both dampers were detailed based on CFD simulations,and their internal fluid flows were investigated.Full-scale specimens of both dampers were manufactured and tested under dynamic loads.According to the tests results,both dampers demonstrate stable cyclic behaviors,and as expected,the nonlinear damper generally tends to dissipate more energy compared to its linear counterpart.Good compatibility was achieved between the experimentally measured damper force-velocity curves and those estimated from CFD analyses.Using a thermography camera,a rise in temperature of the dampers was measured during the tests.It was found that output force of the manufactured devices was virtually independent of temperature even during long duration loadings.Accordingly,temperature dependence can be ignored in CFD models,because a reliable temperature compensator mechanism was used(or intended to be used)by the damper manufacturer.

Analysis of Medical Waste Incinerator Performance Based on Fuel Consumption and Cycle Times

A detailed assessment of an incinerator based on fuel consumption and cycle time data is presented in this paper. The study was conducted at Temeke district hospital for 22 months consecutively covering 654 days of daily data collection on fuel consumption and cycle times. The composition for the medical waste incinerated varied between 15% and 35% for sharps waste and between 65% and 85% for other waste, with mean values of 25% and 75%, respectively. The results revealed poor performance of the incinerator due to higher fuel consumption (above 30 L/cycle). The incineration cycle times were observed to range between 2 and 4 hours, all of which were too high for the loading rates observed (55 - 214 kg). A strong dependency of diesel oil consumption on cycle time was observed due to lack of temperature control leading to continuous fuel flow into the burners. The incineration capacity was very low compared to other incinerators in terms of tons per year. This paper gives an insight on the factors affecting incinerator performance assessed based on diesel oil consumption and cycle times. It can be generalized that the incinerator performance was poor due to several factors ranging from poor incinerator design, operator skills, waste management practices, waste storage practices, etc. The hospital was advised to install a new incinerator with short incineration cycle time (30 - 40 minutes) and lower fuel consumption (10 L/cycle) at a loading rate of 200 kg/cycle.

Application of Hopfield Neural Networks Approach in Solar Energy Product Conceptual Design

A new product conceptual design approach is put forward based on Hopfield neural networks models. By research on the mechanisms of Hopfield neural networks, the associative simulation approaches are proposed. The approach is given by Hebb learn- ing law, Hopfield neural networks and crossover and mutation. The calculating models and the calculating formulas for the concep- tual design are put forward. Finally, an example for the conceptual design of a solar energy lamp is given. The better results are ob- tained in the conceptual design.

An Experimental Investigation of the Factors Which Affect on the Performance of a Single Basin Typical Double Slope Solar Still for Water Desalination

Solar energy is very useful in the process of desalination especially for areas that suffer from a lack of clean water resources. In recent years, many people have been using solar still. Therefore the raising of the productivity and efficiency of solar still represents the most important problems that need further research. The present work aims to study the effect of preheating the water entering to still and the effect of reducing pressure inside the still on the productivity of the solar still. Therefore in present work two identical single basin typical double slope solar stills of the inner basin dimensions for each still 2 m × 1 m × 0.08 m, have been designed and fabricated with mild steel plate. One of them is conventional solar still and the other is modified with flat plate collector and vacuum pump to study the effect of preheating and vacuum on the performance of solar still. The experimental measurements are made to enhance the solar still productivity by firstly preheating the water entering the still using flat plate collector and secondly by integrating the still basin with vacuum pump. The results show that preheating the water entering the still increases the water productivity by amount about 27.7% - 29.3%. The results also show that decreasing pressure inside the still using vacuum pump improves the solar still water productivety by amount about 21.8% - 23.9%.

Mechanical Properties of Lab Joint Composite Structure of Glass Fiber Reinforced Polymers

Glass fiber composite laminates have competitive properties than monotonic material for their superior mechanical strength. Lab joints in composite structure are of great importance in aerospace and aircraft industry. Therefore, lab joints’ strength and failure of composite laminates structure are experimentally investigated. Composites laminates of four different stacking sequences and layup are manufactured using hand layup technique and curing at room temperature. Specimens of unidirectional laminates of [0]8 stacking sequence are used to test lamina mechanical properties while [0/90]2s, [0/60/90]s and woven are used to test the mechanical properties of lab joints. Lab joints of single row and double row are produced and tested in bearing using simple mode I test (tension test). The results illustrate that bearing strength of quasi-brittle laminates of [0/60/90]s has more stability and strength than that of woven glass fiber, then the cross ply laminates of [0/90]2s;this can be attributed to increase of anisotropy of cross ply laminates than other composite laminate structure.

Ornaments as Means of Efficient Reinforcement in Heritage Buildings

Heritage consists of those items people have inherited and want to keep, as they give them the sense of the past of their cultural identity, but these items, especially the buildings, could not face deteriorations during their period of life, such as the change of loads, the act of the environmental conditions, the effect of the duration time of the materials and the misuse of the occupants. They need special treatments and reinforcements to keep the structural state or to gain extra forces to receive the new loads. But the traditional ways of reinforcement do not prove endless solutions as the most means of the deteriorations from the nature. So, the liability issue is how to find the least reinforcement within the means of technology with the least deterioration and in a less time or by other ways efficiently. The hypothesis considers that the ornaments in some heritage buildings are found in critical levels of the construction which can share in an efficient way in the reinforcement processes of such buildings.

Torque Free Axi-Symmetric Gyros with Changing Moments of Inertia

The properties and characteristics of torque free gyros with rotational symmetry and changing moments of inertia are the subject of the subsequent discussion. It shall be understood that the symmetry can be expressed by the notation (A=B) which does not presuppose geometric symmetry, where A and B are the principle moments of inertia about x and y axes respectively. We study the case of a torque free gyro upon which no external torque is acting. The equations of motion are derived when the origin of the xyz-coordinate system coincides with the gyro’s mass center c. This study is useful for the satellites, which have rotational symmetry and changed inertia moments, the antennas and the solar power collector systems.

An Assessment of Air and Water Pollution Accrued from Stone Quarrying in Mukono District, Central Uganda

The unquenchable demand for rock materials has attracted many companies within the building and construction sector to invest in stone quarrying. However, this has brought about environmental impacts with health threats to people. There is a paucity of information about the magnitude of pollution on air and water and how it varies with quarry sites. This study, therefore, investigated the physical impacts of quarrying on air and water and explored the in-situ mitigations to undesirable effects due to stone quarrying. Four active quarry sites were identified. Field measurements of dust (particulate matter) were conducted within the four quarry sites and in the nearby community. Water samples were collected from quarry pits and nearby shallow wells for laboratory analysis of water quality. Statistical Analysis of Variance (ANOVA) was used to test for differences in pollution across the four studied sites. Results revealed that, amidst the use of wet crushing and water sprinkling on bare surfaces, dust emission was higher than the recommended permissible standards levels with a significant variation across the quarry sites with ANOVA (P-value = 0.003) for PM 2.5 and (P-value = 0.04366) for PM 10. Water pollution was mainly contributed by the non-permissive levels of nitrates, chromium, and pH. Polluted air and water are associated with sparking off health threats to the users in the community. In conclusion, quarry companies should strengthen the already existing mitigation of dust suppression. The study recommends additional measures such as treating quarry pit water before discharging to the open environment to enhance environmental protection against the accumulating undesirable quarry impacts.

Estimation of Domestic Solid Waste Amount and Its Required Landfill Volume in Najaf Governorate, Iraq for the Period 2015-2035

Solid waste management is one of the most important challenges facing the local administration in the governorate of Najaf. This paper investigates the domestic amount generated in Najaf governorate for period 2015-2035 and the required landfill volume for the disposal of the waste. The daily per capita waste generation in Al-Najaf is 0.42 kg, the humidity content about 43% and the density of waste around 473 kg/m3. The total amount was about 5,914,415 ton and the required landfill volume is 11,828,829 m3.

Deep Learning-Enhanced Brain Tumor Prediction via Entropy-Coded BPSO in CIELAB Color Space

Early detection of brain tumors is critical for effective treatment planning.Identifying tumors in their nascent stages can significantly enhance the chances of patient survival.While there are various types of brain tumors,each with unique characteristics and treatment protocols,tumors are often minuscule during their initial stages,making manual diagnosis challenging,time-consuming,and potentially ambiguous.Current techniques predominantly used in hospitals involve manual detection via MRI scans,which can be costly,error-prone,and time-intensive.An automated system for detecting brain tumors could be pivotal in identifying the disease in its earliest phases.This research applies several data augmentation techniques to enhance the dataset for diagnosis,including rotations of 90 and 180 degrees and inverting along vertical and horizontal axes.The CIELAB color space is employed for tumor image selection and ROI determination.Several deep learning models,such as DarkNet-53 and AlexNet,are applied to extract features from the fully connected layers,following the feature selection using entropy-coded Particle Swarm Optimization(PSO).The selected features are further processed through multiple SVM kernels for classification.This study furthers medical imaging with its automated approach to brain tumor detection,significantly minimizing the time and cost of a manual diagnosis.Our method heightens the possibilities of an earlier tumor identification,creating an avenue for more successful treatment planning and better overall patient outcomes.

Landfill Site Selection in AI-Najaf Governorate, Iraq

Solid waste management aspect is one of the most important challenges facing the local administration in the Govemorate of Najaf. Therefore, this study aims to provide for solid waste management problem by choosing the best locations for the establishment of sanitary landfills in the governorate. In this study, GIS （geographic information system） and MCDA （multi-criteria decision analysis） were used based on 17 environmental, economic and geological criteria converted to input digital map layers. These were urban centres, cemetery, airports, electrical power lines, oil pipes, railways, roads, slope, historical sites, main rivers, industrial areas, religion sites, wells, military area, electrical power plants, nature reserves and national borders to select most importance sites in the govemorate. AHP （analytic hierarchy process） method was used in weighting the criteria used. All layers＇ maps were graded from 0 （not suitable） to 5 （most suitable） using spatial information scale then SAW （simple additive weighting） method was integrated in GIS used to calculate the suitability index for the studied area. The results indicated that 4.4% of the study region is suitable for landfill siting with grading values greater than 4.0. This included five sites distributed in three qadhaas of governorate.

Ranking Landfill Sites in Najaf Governorate, Iraq Using AHP and Fuzzy TOPSIS Methods

In Najaf Govemorate, Iraq, there are five landfill sites. This study aims to rank these sites based on their criteria which are site capacity, land elevation and land price. AHP （analytic hierarchy process） method was used to weight the criteria and the technique for order preference by similarity to ideal solution. Fuzzy TOPSIS （technique for order of preference by similarity to ideal solution） method was used to rank these sites from best to worst. Based on AHP method, the site capacity criterion was the most important than land price and land elevation.

Corrigendum to“Magnesium cationic cue enriched interfacial tissue microenvironment nurtures the osseointegration of gamma-irradiated allograft bone”[Bioact.Mater.10C(April 2022)32-47]

The authors regret a mistake of funding numbers in the Acknowledgment Section failed to be corrected during proof reading.Below is the corrected funding statement in Acknowledgment SECTION This work was supported by the National Natural Science Foundation of China(NSFC)(Nos.81902189,81772354,82002303,31570980),Clinical Innovation Research Program of Guangzhou Regenerative Medicine and Health Guangdong Laboratory(2018GZR0201002),National Key Research and Development Plan(2018YFC1105103).

Comprehensive performance analysis and optimization of 1,3-dimethylimidazolylium dimethylphosphate-water binary mixture for a single effect absorption refrigeration system

The energy and exergy analyses of the absorption refrigeration system (ARS) using H2O-[mmim][DMP] mixture were investigated for a wide range of temperature. The equilibrium Dühring (P-T-XIL) and enthalpy (h-T-XIL) of mixture were assessed using the excess Gibbs free non-random two liquid (NRTL) model for a temperature range ??? of 20°C to 140°C and XIL from 0.1 to 0.9. The performance validation of the ARS cycle showed a better coefficient of performance (COP) of 0.834 for H2O-[mmim][DMP] in comparison to NH3-H2O, H2O-LiBr, H2O-[emim][DMP], and H2O-[emim][BF4]. Further, ARS performances with various operating temperatures of the absorber (Ta), condenser (Tc), generator (Tg), and evaporator (Te) were simulated and optimized for a maximum COP and exergetic COP (ECOP). The effects of Tg from 50°C to 150°C and Ta and Tc from 30°C to 50°C on COP and ECOP, the Xa, Xg, and circulation ratio (CR) of the ARS were evaluated and optimized for Te from 5°C to 15°C. The optimization revealed that Tg needed to achieve a maximum COP which was more than that for a maximum ECOP. Therefore, this investigation provides criteria to select low grade heat source temperature. Most of the series flow of the cases of cooling water from the condenser to the absorber was found to be better than the absorber to the condenser.

Energy efficiency of small buildings with smart cooling system in the summer

In this paper,a novel cooling control strategy as part of the smart energy system that can balance thermal comfort against building energy consumption by using the sensing and machine programming technology was investigated.For this goal,a general form of a building was coupled by the smart cooling system(SCS)and the consumption of energy with thermal comfort cooling of persons simulated by using the EnergyPlus software and compared with similar buildings without SCS.At the beginning of the research,using the data from a survey in a randomly selected group of hundreds and by analyzing and verifying the results of the specific relationship between the different groups of people in the statistical society,the body mass index(BMI)and their thermal comfort temperature were obtained,and the sample building was modeled using the EnergyPlus software.The result show that if an intelligent ventilation system that can calculate the thermal comfort temperature was used in accordance with the BMI of persons,it can save up to 35%of the cooling load of the building yearly.

A new systematic firefly algorithm for forecasting the durability of reinforced recycled aggregate concrete

This study presents a new systematic algorithm to optimize the durability of reinforced recycled aggregate concrete.The proposed algorithm integrates machine learning with a new version of the firefly algorithm called chaotic based firefly algorithm(CFA)to evolve a rational and efficient predictive model.The CFA optimizer is augmented with chaotic maps and Levy flight to improve the firefly performance in forecasting the chloride penetrability of strengthened recycled aggregate concrete(RAC).A comprehensive and credible database of distinctive chloride migration coefficient results is used to establish the developed algorithm.A dataset composite of nine effective parameters,including concrete components and fundamental characteristics of recycled aggregate(RA),is used as input to predict the migration coefficient of strengthened RAC as output,k-fold cross validation algorithm is utilized to validate the hybrid algorithm.Three numerical benchmark analyses are applied to prove the superiority and applicability of the CFA algorithm in predicting chloride penetrability.Results show that the developed CFA approach significantly outperforms the firefly algorithm on almost tested functions and demonstrates powerful prediction.In addition,the proposed strategy can be an active tool to recognize the contradictions in the experimental results and can be especially beneficial for assessing the chloride resistance of RAC.

Magnesium cationic cue enriched interfacial tissue microenvironment nurtures the osseointegration of gamma-irradiated allograft bone

Regardless of the advancement of synthetic bone substitutes,allograft-derived bone substitutes still dominate in the orthopaedic circle in the treatments of bone diseases.Nevertheless,the stringent devitalization process jeopardizes their osseointegration with host bone and therefore prone to long-term failure.Hence,improving osseointegration and transplantation efficiency remains important.The alteration of bone tissue microenvironment(TME)to facilitate osseointegration has been generally recognized.However,the concept of exerting metal ionic cue in bone TME without compromising the mechanical properties of bone allograft is challenging.To address this concern,an interfacial tissue microenvironment with magnesium cationc cue was tailored onto the gamma-irradiated allograft bone using a customized magnesium-plasma surface treatment.The formation of the Mg cationic cue enriched interfacial tissue microenvironment on allograft bone was verified by the scanning ion-selective electrode technique.The cellular activities of human TERT-immortalized mesenchymal stem cells on the Mg-enriched grafts were notably upregulated.In the animal test,superior osseointegration between Mg-enriched graft and host bone was found,whereas poor integration was observed in the gamma-irradiated controls at 28 days post-operation.Furthermore,the bony in-growth appeared on magnesium-enriched allograft bone was significant higher.The mechanism possibly correlates to the up-regulation of integrin receptors in mesenchymal stem cells under modified bone TME that directly orchestrate the initial cell attachment and osteogenic differentiation of mesenchymal stem cells.Lastly,our findings demonstrate the significance of magnesium cation modified bone allograft that can potentially translate to various orthopaedic procedures requiring bone augmentation.