Search

In this article, we execute the enhanced ( G ' / G )-expansion method to search for new and further general closed-form wave solutions to the nonlinear partial differential equation, namely the Benny Luke equation. This method is one of the powerful techniques that come into view in recent time for establishing more exact wave solutions to nonlinear partial differential equations. We have achieved some new exact solutions including soliton and periodic wave solutions with arbitrary parameters and the solutions are expressed in terms of hyperbolic and trigonometric functions. The efficiency of this method for finding exact solutions has been established. It is shown that the enhanced ( G ' / G )-expansion method is direct, effective and can be used for many other nonlinear partial differential equations in mathematical physics and engineering.

A common problem in pixelwise classification or semantic segmentation is class imbalance, which tends to reduce the classification accuracy of minority-class regions. An effective way to address this is to tune the loss function, particularly when Cross Entropy (CE), is used for classification. Although several CE variants have been reported in previous studies to address this problem, for example, Weighted Cross Entropy (WCE), Dual Cross Entropy (DCE), and Focal Loss (FL), each has their own limitations, such as introducing a vanishing gradient, penalizing negative classes inversely, or a sub-optimal loss weighting between classes. This limits their ability to improve classification accuracy or reduces their ease of use. Focal Loss has proven to be effective at balancing loss by increasing the loss on hard-to-classify classes. However, it tends to produce a vanishing gradient during backpropagation. To address these limitations, a Dual Focal Loss (DFL) function is proposed to improve the classification accuracy of the unbalanced classes in a dataset. The proposed loss function modifies the loss scaling method of FL to be effective against a vanishing gradient. In addition, inspired by DCE, a regularization term has also been added to DFL to constrain the negative class labels to further reduce the vanishing gradient effect and increase the loss on hard-to-classify classes. Experimental results show that DFL has better training performance, and provides greater accuracy compared to CE, WCE, FL and DCE in every test run conducted over a variety of different network models and datasets.

This study reports the influences of gamma irradiation (GI) in the range of 20–100 kGy on CuO thin films via thermal spray pyrolysis technique on the glass substrates. The results demonstrate significant influences of GI on the crystallographic, microstructural and optical characteristics of CuO thin films. The obtained XRD results showed that the crystallinity of the films deteriorates by gradually decreasing crystallite size (from 59.13 to 46 nm) as applied gamma doses increases. However, the basic monoclinic crystal structure remains same. The dislocation density and lattice strain increased with the rise of GI absorbed dose due to the creation of defects. The values of number of crystallites per unit surface area increased as dose increased indicating the abundance of crystallization of nano CuO thin films. A UV–Vis–NIR spectrophotometer was utilized to determine the optical properties and obtained results indicated that the optical energy band gap (OBG) energies reduced from 2.00 to 1.72 eV as the doses increased from 0 to 100 kGy. No distinctions of the monoclinic phase of virgin CuO thin film have been perceived under applied absorbed doses, notwithstanding the slight deterioration of the crystallinity and narrowing the OBG.

This paper focuses on understanding the effect of reticulated porous cathode flow fields in real scale close and open cathode polymer electrolyte membrane fuel cells (PEMFCs) in terms of their thermo-electrical performance. This research contributes to addressing challenges with PEMFCs linked to oxygen supply to the cathode and proper mixing of gasses as well as water removal issues. Parallel channel and porous cathode flow fields in both open and closed cathode PEMFCs of medium scale (active area of 15 × 15 cm2) have been investigated. The porous material consisted of 20 pores per inch with a porosity level of 80%. The cells’ polarisation and impedance characteristics have been analysed. The porous flow field has been found providing better electrical performance in closed cathode PEMFC compared to the open cathode. Improvements in gas diffusion and temperature uniformity were observed with porous flow field; however, water removal has been observed challenging, which need to be addressed before the benefits of using porous flow field are fully realised.

Amalgamation of thermal collector at the back of PV overcomes with low energy conversion efficiency issue upto some extent and improves overall efficiency of the systems. Use of phase change materials (PCM) in PV/T collectors as an intermediate thermal storage media offers a promising solution to this problem by storing large amount of heat. The aim of this research work was to design and develop a photovoltaic/thermal-phase change materials (PV/T-PCM) system and evaluate its energy, exergy and economic performance. Lauric acid as PCM contained in leak-proof aluminum foil packets are placed around the flow channel allowing extended period of thermal storage. The PV/T-PCM system has been studied at different volume flow rates viz. 0.5–4 L per minutes (LPM) to get the optimized performance of the system. Maximum thermal efficiency of PV/T-PCM collector was found to be 87.72% at 2 LPM. Maximum electrical efficiency of PV and PV/T-PCM systems has been found to be 9.88% and 11.08% (4LPM) respectively. The maximum exergy efficiency of PV and PV/T-PCM system has been found 7.09% and 12.19% (0.5 LPM) respectively. An economic analysis of the proposed system has also been carried out with a view to examine the feasibility of its commercialization.

Photovoltaic (PV) technology suffers from the major drawback of poor energy conversion efficiency that is further worsened by overheating of the module. Hybrid photovoltaic thermal (PV/T) collectors have brought about a notable change in this technology by enabling the extraction of both electricity and heat from the same module, thereby improving the overall efficiency. However, there are some technical challenges with these devices that obstacles their wide-scale application. The major shortcoming of conventional water based PV/T collector is that their operation is limited only in the daytime. To overcome these challenges, novel parallel serpentine pipe flow based PV/T has been designed, developed and studied. The experiments were performed at different volume flow rates viz. 0.5–4 L per minutes (LPM) to optimize the designed and developed PV/T. Maximum thermal efficiency of PV/T system was found to be as 76.58% at 2 LPM. Electrical efficiency of PV and PV/T-only was found to be 9.89% and 10.46% respectively. The maximum exergy efficiency of PV and PV/T system has been found 7.16% and 12.98% (0.5LPM) respectively.

This paper deals with flow behaviour through a confined passage filled with metal foams (MFs). Two sets (four samples) of aluminium foams of 20 and 40 ppi pore densities with 9–11% and 12–16% relative densities (RD) individually (as per supplier’s specification) were used for the study. Former RD belonged to uncompressed metal foams whereas the later was achieved by unidirectional compression of metal foam of 6–8% RD. Measured porosities of the uncompressed 20 and 40 ppi MF samples were equal, which was 0.88. However, measured porosities were 0.83 and 0.86 for compressed 20 and 40 ppi MF samples. Flow characteristics of both compressed and uncompressed samples were experimentally measured. Fourie-Plessis’s representative unit cell (RUC) model was used as an analytical tool for estimating pressure drop gradient through MFs because of its simplistic approach and independency from flow characteristics. Possible encasing wall effect on pressure drop was theoretically conducted. Due to a significant difference in estimated and experimentally obtained pressure drop gradient, authors have proposed a modification in the RUC model. The modified version of the RUC model was able to estimate pressure drop gradient of the uncompressed samples with a considerably higher accuracy.

Exogenous ameliorants hold a great potential to strengthen endogenous plant defence under various environmental stresses, including salinity. The effects of Cypress Leaf Extract (CLE, as a biostimulant) and salicylic acid (SA) on growth, physio-biochemical and molecular responses of zucchini (Cucurbita pepo L. cv. Kavili) seedlings under salt stress were investigated. Salt stress resulted in decreased photosynthesis activity and increased oxidative stress. However, CLE- and SA-pretreatment of salt-stressed seedlings enhanced their growth, photosynthetic capacity, antioxidant enzyme (SOD, CAT, APX, GPX, GR, and DHAR) activities and the contents of ascorbate, glutathione and proline as compared to the salt-stressed untreated seedlings. CLE- and SA-pretreatment also alleviated the salt stress-induced negative effects on CO2 assimilation and significantly increased the activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Furthermore, CLE pretreatment also upregulated the expression of stress-inducible antioxidation-related genes (CuZnSOD2, CAT1, APX, GR, DHAR and PrxQ) in salt-stressed seedlings. Interestingly, CLE was found to outperform SA in augmenting these processes under both stress and stress-free conditions. Our study reveals that CLE-mediated enhancement of photosynthesis and antioxidative defence mechanisms plays a crucial role in the alleviation of salt stress, and thereby increasing salt tolerance and growth of zucchini plants.

This work focuses on forced convection through asymmetrically heated rectangular confined porous flow passage of aspect ratio of 50 (width/height = 150/3). Heat transfer characteristics of the porous flow passage were investigated with four different open-cell aluminium metal foams (MF) as porous media. Two sets (four samples) of aluminium foams of 20 ppi and 40 ppi pore densities with each set had two different relative densities (RD) of 9–11% and 12–16% (as per supplier's specification). One set of MFs was uncompressed (9–11% relative density) while another set was obtained by unidirectional compressing the MFs of 6–8% RD and 6 mm height flow passages. The study was systemically conducted with constant heat flux at the bottom surface of the flow passage, and on the basis of compact heat transfer surface analogy. Steady state condition was achieved before acquiring data. Temperature distribution along flow direction was investigated to study thermal development of air flow through it. It was found that thermally developed flow exists in such confined flow passages. Moreover, as a case study of a potential application, a systematic method was followed to obtain performance curves for all the flow passages as compact heat transfer surfaces for use in a Polymer Electrolyte Membrane Fuel Cell(PEMFC). The performance curves were utilised to obtain the best compact heat transfer surface for its possible use in a PEMFC.

High energy photon of gamma radiation interacts with matter and alter physical properties of materials. Optoelectronic and photonic devices, which are placed at space satellite and near radiation source like a nuclear reactor, can be exposed to gamma radiation. Effect of gamma radiation must be investigated before applying a material in a high radiation environment. In this paper, a potential material for optoelectronics and photonic devices, Mg-doped ZnO thin film of 200 nm was fabricated on a glass slide by sol-gel spin-coating method and irradiated with 579.96 Giga gamma photons per second per centimeter square surface area by Co-60 gamma source. Effect of absorbed dose on Mg-doped ZnO thin film was investigated for the first time. Variation of surface morphology, optical properties, and lattice parameters, caused by gamma radiation absorption doses in the range of 0 kGy–100 kGy, was assessed. It is observed that surface morphology is changed significantly with absorbed dose. With non-linear and monotonic fashion, dislocation density and lattice strain tend to increase, whereas crystallite size and bandgap tend to decrease with absorbed dose. Transmittance and absorbance spectra are changed considerably as well.

Phase change materials (PCMs) can be applied to several different solar energy systems for the extended heat energy storage which is quite useful as the solar energy is intermittent in nature and is unavailable during the night period. Application of PCMs in solar energy systems allows the solar energy to be used at any time even in the absence of the natural solar radiation. Thus, the use of PCMs in the solar energy systems can bridge the demand and supply gap of the normal electrical energy. This paper deals with the recent advances in PCMs application in different solar energy systems and presents almost all of the emerging areas where the applications of PCM in solar energy systems are urgently required. The novel and most recent developments of PCMs in solar thermal energy systems, such as, solar thermal power plants, solar air heater, solar water heater and solar cooker have been duly covered. Furthermore, the application of PCMs in heating and cooling of buildings have been presented as well as the investigation of the PCM application in the solar photovoltaic systems for the performance enhancement of PCMs. Intrinsically important, from the study it has been found that PCMs have been in use in almost all of the solar energy systems even though their uses are still limited and commercially not available due to several economic and environmental constraints. Thus, the paper attempts to present recent and novel approaches by the authors around the world on PCMs applications in the solar energy in well documented forms. Based on the findings, future recommendations have also been given to provide the idea and pragmatic concepts for the researcher to work on the areas of research for further improvements in the systems.

A 1320-Megawatt capacity coal-fired power plant is establishing near the Ecologically Critical Area of the Sundarbans, Bangladesh. This power plant will generate 0.71 million tons of coal fly ash annually. Most of the previous studies concentrated on the soil amelioration and growth and yield of agricultural crops. However, this study investigated the effects of coal fly ash on the seedling growth (collar diameter, height, and biomass) of the major tree species (Bruguiera sexangula, Excoecaria agallocha, Heritiera fomes, and Xylocarpus mekongensis) of the Sundarbans, as well as to assess the nutrient (N, P, and K) partitioning in their parts (leaf, stem, and roots). Mangrove soil and coal fly ash were mixed to get seven treatments say T0, T1, T2, T3, T4, T5, and T7, which contained 0%, 5%, 10%, 20%, 30%, 40% and 50% of fly ash (w/w) respectively. A significant (p

Scanning electrochemical microscopy (SECM) has recently been reported as a convenient technique to characterize the apparent diffusion coefficients in porous media ( D ⋆ ) such as lithium-ion battery electrodes. The technique relies on hemispherical diffusion at the probe in the presence and absence of porous media. However, transition towards cylindrical diffusion follows as the diffusion layer becomes comparable to the media thickness, gradually limiting direct correlation between D ⋆ and the SECM probe steady state current. In this work, we examine the experimental parameters that define this transitional frontier using simulations. A best practice thickness criterium is derived that ensures that the measured steady state current is ≳ 90% of that found in the ideal hemispherical case. Below this thickness limit the response was found to follow an empirical formulation with only two variables. Fundamentally, this quantifies diffusion in the transition regime between hemispherical and cylindrical transport. Practically, this correction formulation may be included into standard steady-state current expression to account for the deviation from hemispherical transport in “thin” electrodes. The analysis consolidates SECM as a reliable tool to characterize liquid phase mass transport within porous films over wide range of thicknesses, including films supported on blocking substrates, like lithium-ion battery electrodes.

Application of Radial Basis Function Network (RBFN) to impact force identification.Application of Multilayer Perceptron (MLP) to the same task.Accuracy, success rate and error range comparison between RBFN and MLP.Estimation of accuracy improvement for using RBFN in place of MLP. Impact force identification from response sensors is important especially when force measurement using force sensor is not possible due to the installation or dynamic characteristic altering problems. For example, the bump-excited impact force acting on vehicle wheel or ship collision on an offshore structure. Among various existing impact identification approaches, neural network based force identification method has received great attention because one does not need to have a system model. Thus, it is less likely to be affected by ill-posed problem that often occurs during the inversion process. So far, previous studies focused on solving the impact force identification problem using only the conventional Multilayer Perceptron (MLP). Thus, there is a room for improvement to find an alternate algorithm that has great advantage over MLP. For this reason, this study proposes Radial Basis Function Network (RBFN) for possible further improvement in impact identification task. A comparative study between these two algorithms was conducted via experimental approach. Impact forces were made on a Perspex plate structure which was designed to produce similar dynamic behavior of a typical vehicle. Impact locations were fixed at four edges of the test rig to simulate impact events at a vehicle's wheels. Time-domain peak-to-peak and peak arrival time features were extracted from accelerometer data to use as network inputs. Few training data were taken in the way that they represent the entire range of magnitudes of all trial impacts made throughout the experiment. In overall, RBFN improved the impact localization and quantification accuracies by decreasing 32.98% and 40.91% error respectively compared to MLP. The improvement was mainly due to the RBFN's strong approximation ability and its superior tolerance to experimental noises/uncertainties.

Distributing reactant gases uniformly within a cell to ensure proper delivery of reactants is one the crucial requirements for better performance of a Proton Exchange Membrane fuel cell (PEMFC). This investigation was focused on enhancing flow uniformity and distribution of cathode air in parallel channel flow field of a fuel cell. 2D Computational Fluid Dynamic (CFD) simulations (i.e. using ANSYS) were performed to solve continuity and momentum equations across the cathode flow field. Two main designs with modified headers that provide (i) Z-type, and (ii) combination of Z and U-types parallel channel configurations, were investigated for uniform distribution of gases. Our presented designs were able to allow 60–70% of total flow through frontal 80% of total gas flow field area which was just reversed case compared to conventional design where nearly 80% of flow passes through 20% of total area at the end portion of the gas flow field. Further improvement in flow distributions was observed by segmenting the flow field.

The occurrence rate of death and injury due to road traffic accidents is rising increasingly globally day by day. For several decades, the focus of research has been on getting a deeper understanding of the significant factors that influence the risk of road traffic fatalities. In today's modern world, neural network (NN) approaches play a crucial role in identifying the contributing factors that describe the frequency and severity of road accidents. Over the years, many researchers used neural network models for predicting the impact of such factors on road accident injury severity. Deep learning methods such as the recurrent neural network (RNN) and the convolutional neural network (CNN) has recently been successfully used for the prediction of road accidents and demonstrate their high accuracy and efficiency. This study overview and summarizes the different forms of neural network models such as the single layer perceptron (SLP) neural network, the multilayer layer perceptron (MLP) neural network, the radial basis function (RBF) neural network, the recurrent neural network, and the convolutional neural network used as a prediction method for the severity of road crash injuries and includes a discussion of future planning and difficulties. This article also summarizes the model input parameter or independent variable and output or dependent variable, as well as various performance assessment methods.

Smart grid engineering is the key for a beneficial use of widespread energy resources, it is a modernized electrical grid that uses analog or digital information and communications technology. Renewable energy itself a thrust area of research due to its availability, applicability and environmental friendly nature and the application of smart grid in renewable energy makes it vast and more promising. This fusion enables the efficient use of renewable energies which is a key challenge for now. The present review paper attempts to investigate the role of smart grid in the renewable energy. The introductory section sets the role of renewable energy and distributed power in a smart grid system. Subsections cover the concept and availability of renewable energies, renewable energy power calculation formulae, smart grid concepts and its feasibility, case studied as performed by different researchers around the World, discussion and future recommendations and finally the conclusions from the study. To achieve this, articles from different sources such as internet, reports, conferences and journals of Elsevier, Springer, Tailor and Franacis, Wiley and many more have been collected and reviewed. This paper concludes that renewable energies can be used efficiently and in a smart way by using the smart grids. However, the smart grid technology is not mature enough and needs more research on the same.

The Chevrel phase compounds Mo 6 X 8 ( X = S, Se, Te) are theoretically studied by ab initio methods as potential candidates for battery cathode materials. The voltage profiles are calculated for the cases of various alkaline earth metals (Mg, Ca, Sr, Ba) serving as guest intercalation ions. The Ca ions are shown to offer the practically significant voltage of ∼1.0–1.25 V, with S substitution giving the highest voltage over Se and Te. We further demonstrate that doubling the capacity of such a battery would also be possible by incorporating a second Ca ion near the Mo 6 X 8 cluster. The electronic properties of this material are investigated, revealing that the entire Mo 6 cluster behaves as a redox center. Finally, the ion diffusion barriers are calculated, showing comparable values to existing battery materials. This work demonstrates that the Chevrel phase may be useful as a cathode material for intercalating divalent ions, and also offers insights into possible tuning of cathode properties by judicious selection of the constituents.

In this paper, we reported the investigations of the structural, optical and photoluminescence properties of 3 at % Ba-doped SnO2 (SnO2:Ba) thin films under various annealing temperatures. X-ray diffraction analysis exhibits that the SnO2:Ba thin films have a polycrystalline tetragonal rutile structure of SnO2 phase and a nanometric dimension. The post-annealing treatment improves the crystallinity and decreases the crystal imperfections such as lattice strain and dislocation density. Field emission scanning electron microscopy analysis shows that the annealing treatment increases the crystallites agglomeration and minimizes the void fraction in the films. Based on the results, the maximum transmittance of 90%, the lowest resistivity of 6.95 × 10−4 Ω cm and the highest Haacke's figure of merit of 5.02 × 10−3 Ω−1 are obtained for the film annealed at 873 K. The UV–Vis spectra reveal that as the annealing temperature increases from 673K to 873 K, the transmittance threshold is blue-shifted which indicates the systematic increase in the optical band gap (3.19–3.85 eV) of the SnO2:Ba samples. Moreover, we have discussed the dispersion parameters, dielectric constants, nonlinear refractive index and third-order nonlinear susceptibility. A dominant visible emission band at ~ 486 nm is observed for the as-deposited sample, whereas the samples annealed at 773 and 873 K exhibit a high intense near band edge emission in the ultraviolet region.

Conventional channel flow fields of open cathode Polymer Electrolyte Membrane Fuel Cells (PEMFCs) introduce some challenges linked to humidity, temperature, pressure and oxygen concentration gradients along the conventional flow fields that reduce the cell performance. According to previous experimental reports, with conventional air flow fields, hotspot formation due to water accumulation in Gas Diffusion Layer (GDL) is common. Unlike continuous long flow passages in conventional channels, metal foams provide randomly interrupted flow passages. Re-circulation of fluid, due to randomly distributed tortuous ligaments, enhances temperature and humidity uniformity in the fluid. Moreover, the higher electrical conductivity of metal foams compared to non-metal current collectors and their very low mass density compared to solid metal materials are expected to increase the electrical performance of the cell while significantly reducing its weight. This article reviews the existing cooling systems and identifies the important parameters on the basis of reported literature in the air cooling systems of PEMFCs. This is followed by investigating metal foams as a possible option to be used within the structure of such PEMFCs as an option that can potentially address cooling and flow distribution challenges associated with using conventional flow channels, especially in air-cooled PEMFCs.

Optical characteristics besides unique thermo-physical properties of nanoparticles have encouraged researchers to use nanofluids in solar energy collectors or reservoirs as electromagnetic wave absorbing media. Recently, different analyses and approaches have been proposed by researchers. However, the appropriate electro-magnetic phenomenon of nanofluids is not established till date because of the complex dependence between nanoparticles and base fluids. In this work, optical properties of nanofluids are discussed on the basis of published data; mostly used models are presented along with their limitations and applications.

Solar energy is one of the cleanest forms of energy sources and considered as a green source of energy. Solar energy benefit ranges from low carbon emission, no fossil fuel requirement, long term solar resources, less payback time and other. However like other power generation sources, solar energy has also some Safety, Health and Environmental (SHE) concerns. This paper presents the overview of solar energy technologies and addresses the SHE impact of solar energy technologies to the sustainability of human activities. This paper will also recommend the possible ways to reduce the effect of potential hazards of widespread use of solar energy technologies.

The effect of thermal conductivity of the absorber plate of a solar collector on the performance of a thermo-siphon solar water heater is found by using the alternative simulation system. The system is assumed to be supplied of hot water at 50 °C and 80 °C whereas both are used in domestic and industrial purposes, respectively. According to the Rand distribution profile 50, 125 and 250 l of hot water are consumed daily. The condition shows that the annual solar fraction of the planning functions and the collector's configuration factors are strongly dependent on the thermal conductivity for its lower values. The less dependence is observed beyond a thermal conductivity of 50 W/m °C for the solar improper fraction and above 100 W/m °C for the configuration factors. In addition, the number of air ducts and total mass flow rate are taken to show that higher collector efficiency is obtained under the suitable designing and operating parameters. Different heat transfer mechanisms, adding natural convection, vapor boiling, cell nucleus boiling and film wise condensation is observed in the thermo-siphon solar water heater with various solar radiations. From this study, it is found that the solar water heater with a siphon system achieves system characteristic efficiency of 18% higher than that of the conventional system by reducing heat loss for the thermo-siphon solar water heater.

The cement subsector consumes approximately 12–15% of the total industrial energy use. Therefore, this subsector releases CO2 emissions to the atmosphere as a result of burning fossil fuels to produce energy needed for the cement manufacturing process. The cement industry contributes about 7% of the total worldwide CO2 emissions. This study complied a comprehensive literature in terms of Thesis (MS and PhD), peer reviewed journals papers, conference proceedings, books, reports, websites for emission generation and mitigation technique. Emission released associated with the burning of fuels have been presented in this paper. Different sources of emissions in a cement industry has been identified and presented in this study. Different techniques to reduce CO2 emissions from the cement manufacturing industries are reviewed and presented in this paper. The major techniques are: capture and storage CO2 emissions, reducing clinker/cement ratio by replacing clinker with different of additives and using alternative fuels instead of fossil fuels. Apart from these techniques, various energy savings measures in cement industries expected to reduce indirect emissions released to the atmosphere. Based on review results it was found that sizeable amount of emission can be mitigated using different techniques and energy savings measures.

The purpose of this study is to evaluate performance cement of production and cement kiln. The design of energy efficient dryers employing heat pump systems and the dynamic response of the product to the kiln conditions must take into account. In this paper, the formulation of a dynamic and kiln-wide drying model is described. The model predictions have been verified by comparing them with the published experimental data. The model is then used to simulate performance of three industrial kilns. Numerical experiments are carried out to investigate influence of key operating and design parameters on energy consumption of kilns. The model is also used to explore the possibility of manipulating temperature profile within the kiln to reduce energy consumption per tonne of clinker. Cement kiln dust is a fine-grained material produced during the manufacture of cement. At present reuse option is limited and the bulk of cement kiln dust that is not reused in the cement manufacturing process is sent to landfills or stored on-site. Due to the calcium oxide (CaO) content of cement kiln dust, it has the potential to be used as a replacement for lime in treating acidic wastewaters such as acid rock drainage. Slaking of two of the cement kiln dust samples with the highest free lime contents (e.g., 34% and 37% free of CaO) gave elevated pH values statistically comparable to those of the commercial quicklime sample that was characterized as having 87% of CaO. Acid neutralization trials indicate that cement kiln dust samples with low free lime contents could be effective at neutralizing acidic wastewaters.

The cement sub-sector consumes approximately 12–15% of total industrial energy use. Therefore, a state of art review on the energy use and savings is necessary to identify energy wastage so that necessary measures could be implemented to reduce energy consumption in this sub-sector. In this paper energy use at different sections of cement industries, specific energy consumption, types of energy use, details of cement manufacturing processes, various energy savings measures were reviewed and presented. Various energy savings measures were critically analyzed considering amount of energy that can be saved along with the implementation cost. Amount of CO2 reduction has been presented along with the payback period for different energy savings measures as well. This study complied a comprehensive literature on the cement industries in terms of Thesis (MS and PhD), peer reviewed journals papers, conference proceedings, books, reports, websites. It has been observed that China producing major share of global cement production. Coal contribute major share of fuel used in cement industries. However, along with conventional fuels, industries are moving towards the use of alternative fuels to reduce environmental pollution. It was reported that cement industries are moving from wet process to dry process as it consume less energy compared to wet process.

Recently scientists used nanoparticles in refrigeration systems because of theirs remarkable improvement in thermo-physical, and heat transfer capabilities to enhance the efficiency and reliability of refrigeration and air conditioning system. In this paper thermal–physical properties of nanoparticles suspended in refrigerant and lubricating oil of refrigerating systems were reviewed. Heat transfer performance of different nanorefrigerants with varying concentrations was reviewed and review results are presented as well. Pressure drop and pumping power of a refrigeration system with nanorefrigerants were obtained from different sources and reported in this review. Along with these, pool boiling heat transfer performance of CNT refrigerant was reported. Moreover, challenges and future direction of nanofluids/nanorefrigerants have been reviewed and presented in this paper. Based on results available in the literatures, it has been found that nanorefrigerants have a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations than conventional refrigerant. This can be considered as one of the key parameters for enhanced performance for refrigeration and air conditioning systems. Because of its superior thermal performances, latest upto date literatures on this property has been summarized and presented in this paper as well. The results indicate that HFC134a and mineral oil with TiO2 nanoparticles works normally and safely in the refrigerator with better performance. The energy consumption of the HFC134a refrigerant using mineral oil and nanoparticles mixture as lubricant saved 26.1% energy with 0.1% mass fraction TiO2 nanoparticles compared to the HFC134a and POE oil system. It was identified that fundamental properties (i.e. density, specific heat capacity, and surface tension) of nanorefrigerants were not experimentally determined yet. It may be noted as well that few barriers and challenges those have been identified in this review must be addressed carefully before it can be fully implemented in refrigeration and air conditioning systems.

The commercial sector consumes 8–50% of the total energy consumption for a few selected countries around the world. An energy audit was conducted in a Malaysian public hospital to identify energy using equipment and their energy consumption breakdown. Different energy saving measures have been identified and applied for electrical motors used in this hospital. It was estimated that this hospital consumed about 19,311 MW h for the year 2008. It was also estimated that about 212 MW h, 250 MW h and 317 MW h of annual energy can be saved using energy-efficient motors at 50%, 75% and 100% loads, respectively. In addition, use of variable speed drives are expected to save 1735 MW h, 4048 MW h and 6361 MW h of annual energy consumption for 20%, 40% and 60% speed reductions, respectively. It was found that the payback period for using high efficiency motors at different loads is less than a year which is economically very viable. However, the use of variable speed drives was found to be economically viable for larger motors for higher speed reductions. The study also found that a sizeable amount of emissions can be reduced for the different energy savings measures applied for electrical motors.

The road traffic systems, travel patterns and other traffic characteristics are different for each country due to differences in geometric patterns of a country, available transport facilities for commuters, rate of development in the transport sector and so on. Consequently, many standard relations and factors used in one region may not be suited for others. Therefore, an issue comes up to determine the different traffic engineering parameters which are appropriate to local urban transport system characteristics. One such endeavor is to determine the passenger car equivalent (PCE) at signalized intersections for the Dhaka Metropolitan City in Bangladesh where traffic characteristics are completely different from any other cities of the world. PCE currently used in Bangladesh is based on the values given in Geometric Design of Highways (MoC, 2001), which is the modification of the values given by Webster (1958) on the study performed in the United Kingdom in the 50's and 60's. But now-a-days, the situation is far different both for traffic and road user as the characteristics have changed from that time. Hence, in this paper an empirical study was carried out to determine the PCE of different types of vehicle that reflect the actual traffic conditions of Dhaka Metropolitan City. Data were collected from ten signalized intersections and the headway ratio method was used to estimate the PCE of different types of vehicle. The main vehicle compositions observed during the study period consist of passenger cars, auto-rickshaws, mini-buses and buses. The PCE obtained in this study were compared to the values established earlier. It was found that the estimated PCE are smaller than those being used in Bangladesh.