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In this work, four energetic nitrates, i.e., 4,7-diamino-1H-[1,2,3]triazolo[4,5-d]pyridazin-5-ium nitrate (1), 2,6-diamino-1‑hydroxy-9H-purine-1,7-diium nitrate (2), 6-amino-[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazin-2-ium nitrate (3) and 3,6-diamino-[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazin-2-ium nitrate (4), were prepared and comprehensively characterized. The X-ray diffraction results indicated that compounds 1–4 had different layered structures with the densities in the range of 1.616–1.805 g/cm3. The highest density value of 1.805 g/cm3 was represented in compound 2, which was higher than that of most other nitrates. Moreover, compounds 1–4 had good thermal stabilities, the decomposition temperatures were in the ranged of 165–181 °C, which made them have great potential to further develop. The calculated detonation velocities and detonation pressures of these compounds were in the range of 7678–8925 m/s, and 21.96–32.39 GPa, respectively. The greatest detonation velocity and detonation pressure were observed in compound 3. The specific impulses of these compounds were in the range of 199.8–244.9 m/s. Notably, compound 1 had near infrared laser (λ = 1064 nm) ignition capacity, which was the first example of CHNO based energetic compound with near infrared laser ignition performance.

Context: 3,4-Bisnitrofurazanfuroxan (DNTF) is a typical high energy density compound (HEDC), it has high crystal density and detonation parameters, but also high mechanical sensitivity. To decrease its mechanical sensitivity, the DNTF based polymer bonded explosives (PBXs) was designed. The pure DNTF crystal and PBXs models were established. The stability, sensitivity, detonation performance and mechanical properties of DNTF crystal and PBXs models were predicted. Results show that PBXs models containing fluorine rubber (F2311) and fluorine resin (F2314) have higher binding energy, meaning that DNTF/F2311 and DNTF/F2314 is relatively more stable. PBXs models have higher value of cohesive energy density (CED) than pure DNTF crystal, DNTF/F2311 and DNTF/F2314 have the highest value of CED, implying that the sensitivity of PBXs is effectively decreased, DNTF/F2311 and DNTF/F2314 is more insensitive. PBXs have lower crystal density and detonation parameters than DNTF, the energy density is declined, DNTF/F2314 has higher energetic performance than other PBXs. Compared with pure DNTF crystal, engineering moduli (tensile modulus, shear modulus, bulk modulus) of PBXs models are obviously decreased, but Cauchy pressure is increased, implying that the mechanical properties of PBXs is superior to pure DNTF component, the PBXs containing F2311 or F2314 have more preferable mechanical properties. Consequently, DNTF/F2311 and DNTF/F2314 have the best comprehensive properties and is more attractive among the designed PBXs, indicating that F2311 and F2314 are more advantageous and promising in ameliorating properties of DNTF. Methods: The properties of DNTF crystal and PBXs models were predicted through molecular dynamics (MD) method under Materials Studio 7.0 package. The MD simulation was performed with isothermal-constant volume (NVT) ensemble, and the force field was chosen as COMPASS force field. The temperature was set as 295 K, the time step was 1 fs and the total MD simulation time was 2 ns. [ABSTRACT FROM AUTHOR]

Currently, the development of energy production projects in the building sector using alternative energy sources such as solar energy is growing rapidly. This increasing technological progress to achieve the needs of comfort and safety can be considered a major priority, particularly with concerns about energy shortages and current environmental issues threatening not only human well-being but ecosystems as well. The present research aims to provide a comprehensive model for enhancing the energetic performance of rural Moroccan houses, by exploring solar radiant heating systems. The evaluation of the solar floor heating system is carried out by trnsys to evidence the effect of various design parameters on performance indexes of the system concerning six Moroccan cities, which representatively correspond to the Moroccan climatic zoning. The examined analyses cover the effect of the collector area, storage tank volume, and mass flowrate in the solar loop and the building heating loop. Moreover, how the variation of thickness and piping material affect the performances was discussed as well. The major finding of this work is optimizing the system performance gives the possibility to meet adequately the heating load. The energetic analysis shows the system's adaptability to the Moroccan climate, whose solar fraction is around 65% and 87%. For most of the examined sites, it was observed that the demand for auxiliary energy is limited from October to May. The economic investigations revealed that payback periods of the examined system ranged between 7 and 13 years. Besides, the energy and economic outcomes of such systems in Morocco, they are capable to mitigate the huge amount of CO2 emissions as compared to conventional heating systems. [ABSTRACT FROM AUTHOR]

Crystal defect in energetic materials will directly affect its crystal structure and physicochemical properties, including mechanical sensitivity, thermal stability, mechanical properties, energetic performance, etc. In this article, the primitive and defective CL-20/HMX cocrystal models were established and the influence of crystal defects (including adulteration defect, dislocation defect and vacancy defect) on properties of CL-20/HMX cocrystal explosive was investigated by MD method. Results show that the trigger bond strength (N–N chemical bond) of CL-20 molecules in defective CL-20/HMX cocrystal models is lower than primitive cocrystal model and the mechanical sensitivity is increased. Compared with primitive cocrystal model, the binding energy between CL-20 and HMX molecules in defective models is decreased, meaning that the stability of defective models is weakened. The primitive cocrystal model has higher value of shear modulus, tensile modulus, and bulk modulus and lower value of Cauchy pressure than defective models, indicating that the rigidity and rupture strength of defective models are lowered. The density and detonation performance of defective CL-20/HMX cocrystal models are lower than primitive model, implying that the energy density is declined. Therefore, crystal defect can bring a negative influence on mechanical sensitivity, stability and energetic performance of CL-20/HMX cocrystal explosive, and the effect of vacancy crystal defect is more obvious and severe. [ABSTRACT FROM AUTHOR]

All-nitrogen materials, as a unique branch of energetic materials, have gained huge attentions, of which cyclo-N5− derivatives are the representative synthetically reported materials. However, the energetic performance of cyclo-N5− compounds has certain limitations and cannot go beyond that of CL-20. In order to reach the higher energy, in this work, we presented two kinds of polynitrogen species, N4 and N8. Two isomers of N4 and four isomers of N8 were fully calculated by using density functional theory (DFT). Theoretical results show that all these polynitrogen materials exhibit excellent heats of formation (7.92–16.60 kJ g−1), desirable detonation performance (D: 9766–11620 m s−1; p: 36.8–61.1 GPa), as well as the remarkable specific impulses (330.1–436.2 s), which are much superior to CL-20. Among them, N4-2 (tetraazahedrane) (D: 10037 m s−1; p: 40.1 GPa; Isp: 409.7 s) and cube N8-4 (D: 11620 m s−1; p: 61.1 GPa; Isp: 436.2 s) have the highest energetic properties, which are expected to become promising high-energy-density-materials. Moreover, electrostatic surface potentials, Frontier molecular orbitals, infrared spectra, natural bond orbital charges, and weak interactions were also investigated to further understand their relationship between structure and performance.

The crystal models of trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin (TNAD), hexanitrohexaazaisowurtzitane (CL-20), and CL-20/TNAD cocrystal explosive with different component ratios were established. Molecular dynamics (MD) method was applied to predict the stability, sensitivity, energetic properties, and mechanical properties. The effect of component ratio on properties of CL-20/TNAD cocrystal explosive was investigated and estimated. Results show that the cocrystal model with component ratio in 1:1 exhibits the highest binding energy and it is more stable. In CL-20/TNAD cocrystal explosive, the interaction energy of trigger bond is increased by 0.8 ~ 15.0 kJ/mol, implying that the mechanical sensitivity of CL-20/TNAD cocrystal explosive is lower than CL-20 and the safety is effectively improved. Compared with raw CL-20, the crystal density of cocrystal explosive is declined by 0.014 ~ 0.193 g/cm3, detonation velocity is declined by 39 ~ 755 m/s, and detonation pressure is declined by 0.95 ~ 11.40 GPa; namely the energy density of CL-20/TNAD cocrystal explosive is lower than CL-20. The cocrystal explosives with component ratio in 10:1 ~ 1:1 still exhibit desirable detonation performance and can be regarded as high energy density explosives. The values of tensile modulus, shear modulus, and bulk modulus of CL-20/TNAD cocrystal explosive are decreased by 0.448 ~ 10.285 GPa, 0.195 ~ 4.189 GPa, and 0.194 ~ 6.292 GPa, respectively, Cauchy pressure is increased by 0.990 ~ 5.704 GPa, meaning that the rigidity, fracture strength, and hardness of cocrystal explosive are declined, while the plastic property and ductility are increased and the mechanical properties are improved. The cocrystal model with component ratio in 1:1 has the best mechanical properties. Consequently, the CL-20/TNAD cocrystal explosive with component ratio in 1:1 is more stable and insensitive; it also has high energy density and the best mechanical properties and may be an attractive candidate for high energy explosives. [ABSTRACT FROM AUTHOR]

Artificial neural networks (ANNs) have been considered for assessing the potential of low GWP refrigerants in experimental setups. In this study, the capability of using R449A as a lower GWP replacement of R404A in different temperature levels of a supermarket refrigeration system is investigated through an ANN model trained using field measurements as input. The supermarket refrigeration was composed of two indirect expansion circuits operated at low and medium temperatures and external subcooling. The results predicted that R449A provides, on average, a higher 10% and 5% COP than R404A at low and medium temperatures, respectively. Moreover, the cooling capacity was almost similar with both refrigerants in both circuits. This study also revealed that the ANN model could be employed to accurately predict the energy performance of a commercial refrigeration system and provide a reasonable judgment about the capability of the alternative refrigerant to be retrofitted in the system. This is very important, especially when the measurement data comes from field measurements, in which values are obtained under variable operating conditions. Finally, the ANN results were used to compare the carbon footprint for both refrigerants. It was confirmed that this refrigerant replacement could reduce the emissions of supermarket refrigeration systems. [ABSTRACT FROM AUTHOR]

Glasfassaden spielen in der modernen Architektur eine zentrale Rolle. Sie öffnen den Blick nach außen und bringen Tageslicht nach innen. Diese Transparenz bringt aber auch verschiedene bauphysikalische und energetische Herausforderungen mit sich, denen man auf unterschiedliche Weise begegnen kann. Verschiedene Technologien können dabei helfen, klimaangepasste und ressourcenschonende Fassaden zu planen und zu bauen: Während der Planungsphase sind Simulationen und präzise Modellierungsstrategien ein wichtiges Werkzeug; eine dynamische Anpassungsfähigkeit der Fassade hinsichtlich ihrer Transparenz und ihrer bauphysikalischen Eigenschaften könnte in Zukunft einen weiteren wichtigen Schritt Richtung Ressourcen‐ und Energieeffizienz bedeuten. Der vorliegende Artikel präsentiert ausgewählte Forschungsansätze und einige aktuelle Projektbeispiele, die aufzeigen, wie nachhaltige Fassadensysteme in der Zukunft aussehen könnten. Sustainable facades: case studies in research and praxis. Glass facades play an important role in modern architecture: they open the view to the outside and let natural light inside. Their transparency entails certain energetic challenges, which can be addressed in different ways. Technologies can support the design process, in order to build sustainable facades and optimize overall use of resources. Today simulation and modelling software are already a useful tool during the design phase; in the future adaptive facade systems could provide answers to the quest for more energy and resource efficiency. This paper presents recent research work as well as innovative case studies, which show a variety of answers to the demand for more sustainable facades. [ABSTRACT FROM AUTHOR]

An analysis of the experimental data available to date shows that the explosive TKX‐50 has really high explosive performance characteristics, although not as outstanding as claimed previously, due to the overestimation of the enthalpy of formation. The obtained experimental data on the dependence of the detonation velocity on the density of TKX‐50 samples agree with the results of calculations, in which the experimentally determined enthalpy of formation 194.1 kJ mol−1 is used. The energetic performance of TKX‐50 surpasses the parameters of nitramines RDX, HMX, and even CL‐20, determined at the same densities. However, the calculated detonation velocity of TKX‐50 at theoretical maximum density is 9287 m s−1, which is slightly lower than the detonation velocity of CL‐20 at maximum density. It is worth noting that the detonation velocity of the TKX‐50 at the experimentally attainable density (1.8 g cm−3) is 9037 m s−1. Calculations using the experimentally determined enthalpy of formation show that high‐energy composite propellant formulations containing TKX‐50 are inferior in a specific impulse to compositions based on CL‐20 and HMX. [ABSTRACT FROM AUTHOR]

Indirect solar dryers represent a clean and sustainable solution for drying foods, fruits, and vegetables. In this research, the performance of a novel indirect hybrid solar dryer has been investigated numerically on apple slices using TRNSYS software. The solar dryer consists of a flat plate solar collector, a vacuum tube solar collector, a cross-flow heat exchanger, an auxiliary heater, and a drying chamber. With the assumption that there is no access to fresh fruits and vegetables in winter, the simulation was carried out in three days on April 15, July 15, and October 15 (from 8 a.m. to 5 p.m.) as representatives of spring, summer and autumn, respectively. The humidity content of apple slices reduced from 86 % to 11 % in about 270 min at 70 °C. The minimum power received from the auxiliary heater was on July 15 with 1497 W, which was about 1.5 h without needing a backup heater. (from 11:30 a.m. to 1 p.m.). The maximum thermal efficiency of the drying system was obtained on July 15 at about 60 % for the flat plate collector, 78 % for the vacuity tube collector, and 25 % for the drying chamber. Also, the return on capital in Iran, USA, UAE, and Turkey was equal to 1.49, 0.74, 0.95 and 1.35, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

The main objective of the performed investigations was an analysis of baffles of various construction and production technology with respect of usable energy demand. The investigations encompassed calculations of the energetic performance of fatteners’ piggery building as well as heat and humidity calculations of baffles. The energetic calculations were performed for two variants of execution and heat insulation of external baffles as well as two variants of roofs. The analysis contained the baffles made in two technologies: industrialized and traditional modernized, for three climate zones. For the individual variants, the usable energy demand in heating season as well as specific usable energy demand per one fattener were calculated.

This study shows the performance of a currently running vertical roller coal mill (VRM) in an existing coal-fired power plant. In a power plant, the coal mill is the critical equipment, whose effectiveness impacts the overall power plant efficiency. Uniform coal feeding mass flow rate and required particle size and temperature at the outlet channel throughout with better classifier performance are crucial indicators that characterize the coal mill performance. To understand the performance of a vertical roller coal mill, the real operational tests have been performed considering three different coal sources. Obtained results indicate that grinding pressure, primary air (PA) temperature and mill motor current have a tendency to rise by increasing coal feeding mass flow rates for all used coal. Moreover, coal volatile matter and moisture content are improved by increasing the mill outlet temperature for each coal type. Additionally, effect of enhancement of the classifier speed has been found favorable on the combustion performance indicators. CMC coal shows relatively better performance since it has lower moisture content and higher hard grove index. Ultimately, the energetic efficiency of coal mill has been investigated and performance value has been found to be a maximum value of 96.2%. [ABSTRACT FROM AUTHOR]

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Nitrogen-rich polymers were synthesized by reaction between diazides and dinitriles derivatives in the presence of ammonium chloride as catalyst. All prepared substances were identified by utilize NMR and IR spectroscopy. Thermal stability was determined by using (DSC) and (TGA) which indicated that they have high (Tg 253-262 °C) and good thermal stability under N2 atmosphere. All compounds are thermally highly stable materials. [ABSTRACT FROM AUTHOR]

Modern composite solid propellants must exhibit excellent mechanical properties together with high energy outputs, and the binder system plays a vital role in establishing these characteristics. In the present work, varying proportions of a novel hyperbranched multi‐arm azide copolyether (POG) were combined with a hydroxyl‐terminated polyether (HTPE) to prepare crosslinked elastomeric binders. The compatibility of the POG and HTPE was demonstrated before a series of HTPE/POG blend binders were prepared based on a urethane reaction using hexamethylene diisocyanate (HMDI) as the curing agent. The mechanical properties of HTPE/POG/HMDI elastomers were found to be superior to those of traditional HTPE/N100 crosslinked binders as a result of the formation of a hyperbranched crosslink structure. Evaluations of the local motions of polymers chains and parameters related to the cured network structure demonstrated the advantages of introducing the hyperbranched POG. Hydrogen bonding in the HTPE/POG/HMDI binder was investigated and the results confirmed that these elastomers also benefited from hydrogen bonding, as well as the entanglement and interpenetration of molecular chains. Decomposition behavior was studied by thermogravimetric analysis, differential thermogravimetry and differential scanning calorimetry, and the new binders exhibited good thermal stability and superior energetic performance that could potentially meet the requirements for military applications. [ABSTRACT FROM AUTHOR]

Up until the industrial revolution, energy consumption was relatively linear, and almost exclusively renewable. The exponential industrial and economic development that began with the industrial revolution became increasingly energy-intensive, and since the switch to fossil fuels that energy consumption has been based on non-renewable resources. Satisfying the energy needs of the present without harming future generations remains a complicated problem, especially at the habitat level. This article proposes a methodology for building designers, building upon research on converging towards a global optimum, more specifically, it investigates the feasibility of integrating mezzanines and vaults as vernacular devices to improve the energy performance of buildings in arid zones, while to ensuring the comfort of the occupants. This level of comfort and energy performance is based on the morphological structure of the proposed building type. Combined, these devices result in a higher reduction of thermal in energy ratio load of up to 20.84%. These reductions in energy needs were achieved by applying the methodology developed for the architectural design of a building located in Biskra, Algeria, a design that takes into account both the comfort aspects of the occupants and the need for reduced energy consumption. [ABSTRACT FROM AUTHOR]

Artificial neural networks (ANNs) have been considered for assessing the potential of low GWP refrigerants in experimental setups. In this study, the capability of using R449A as a lower GWP replacement of R404A in different temperature levels of a supermarket refrigeration system is investigated through an ANN model trained using field measurements as input. The supermarket refrigeration was composed of two indirect expansion circuits operated at low and medium temperatures and external subcooling. The results predicted that R449A provides, on average, a higher 10% and 5% COP than R404A at low and medium temperatures, respectively. Moreover, the cooling capacity was almost similar with both refrigerants in both circuits. This study also revealed that the ANN model could be employed to accurately predict the energy performance of a commercial refrigeration system and provide a reasonable judgment about the capability of the alternative refrigerant to be retrofitted in the system. This is very important, especially when the measurement data comes from field measurements, in which values are obtained under variable operating conditions. Finally, the ANN results were used to compare the carbon footprint for both refrigerants. It was confirmed that this refrigerant replacement could reduce the emissions of supermarket refrigeration systems.

The anaerobic digestion plant studied in this paper is one of the first full-scale plants using olive oil by-products. This is a two-stage plant with a power of 100 kWe. Two tests were performed: the first on olive pulp and pitted pomace and the second on biomass consisting of 10% crushed cereal. In both cycles, the retention time was 40 days. The production of biogas was between 51 and 52 m3/h, with limited fluctuations. The specific production values of biogas indicate that a volume of biogas greater than 1 m3/kg was produced in both tests. The produced biogas had a methane percentage of about 60% and the specific production (over total volatile solids, TVS) of methane was of the order of 0.70 m3methane/kgTVS. FOS/Alk (ratio between volatile organic acids and alkalinity) was always lower than 1 and tended to decrease in the second digester, indicating a stable methanogenic phase and the proper working of the methanogenic bacteria in the second reactor. The concentration of incoming biomass TPC (total polyphenols content) can vary significantly, due to the seasonality of production or inadequate storage conditions, but all measured values of TPC, between 1840 and 3040 mg gallic acid kg−1, are considered toxic both for acidogenic and methanogenic bacteria. By contrast, during the process the polyphenols decreased to the minimum value at the end of the acidogenic phase, biogas production did not stop, and the methane percentage was high.

This paper reports an experimental comparison between the use of the refrigerants R409A and R437A in a heat pump unit designed and developed to work with R12. Although the use of both refrigerants in new equipments were abolished in EU and US according the new F-Gas Regulation of EU and SNAP, they still being used as options for R12 in old equipments, especially in developing countries. Both refrigerants were studied for the same test conditions, according to two groups of tests: group A (variation of the heat source temperature) and group B (variation of refrigerant flow rate). The results obtained showed that the R437A presents a higher discharge pressure and a lower discharge temperature. The heating and cooling capacities of both refrigerants were similar, as well as the exergetic efficiency. For the group A of tests the COP of both refrigerants was similar and for the group B of tests the R409A presented an average COP 15% higher. According to the results obtained it is recommended the use of R409A in old equipments (as transition refrigerant) until the acquisition of equipments operating with refrigerants with low-GWP becomes technically and economic feasible.

The main objective of the performed investigations was an analysis of baffles of various construction and production technology with respect of usable energy demand. The investigations encompassed calculations of the energetic performance of fatteners' piggery building as well as heat and humidity calculations of baffles. The energetic calculations were performed for two variants of execution and heat insulation of external baffles as well as two variants of roofs. The analysis contained the baffles made in two technologies: industrialized and traditional modernized, for three climate zones. For the individual variants, the usable energy demand in heating season as well as specific usable energy demand per one fattener were calculated. [ABSTRACT FROM AUTHOR]

• Predicting the energetic performance of a BIPVT system using ANN, ANFIS and GA. • Definition of PEC to examine the overall performance of the BIPVT system. • Better performance of ANN model compared with the GA and ANFIS. The main motivation of this study is to evaluate and compare the efficacy of three computational intelligence approaches, namely artificial neural network (ANN), genetic programming (GP), and adaptive neuro-fuzzy inference system (ANFIS) in predicting the energetic performance of a building integrated photovoltaic thermal (BIPVT) system. This system is capable of cooling PV panels by ventilation/exhaust air in winter/summer and generating electricity. A performance evaluation criterion (P E C) is defined in this study to examine the overall performance of the considered BIPVT system. Then, the mentioned methods are used to identify a relationship between the input and output parameters of the system. The parameter P E C is considered as the essential output of the system, while the input parameters are the length, width, and depth of the duct underneath the PV panels and air mass flow rate. To evaluate the accuracy of produced outputs, two statistical indices of R2 and RMSE are used. As a result, all models presented excellent performance where the ANN model could slightly perform better performance compared to GP and ANFIS. Finally, the equations belonging to ANN and GP models are derived, and the GP presents a more suitable formula, due to its simplicity of use, simplicity of concept, and robustness. [ABSTRACT FROM AUTHOR]

• A hybrid solar dryer of wood is successfully modeled using TRNSYS software. • Maximum discrepancy between numerical and experimental results does not exceed 10%. • Energetic and environmental performance of the wood dryer system are investigated. • Energy provided by the auxiliary is higher during winter and lower during summer. • 34% of CO 2 emissions are annually avoided by using a solar compound collector. The aim of this work is to develop a numerical model for investigating the performance of an indirect hybrid solar dryer of wood using TRNSYS software. A solar compound parabolic concentrator (CPC) is used to produce thermal energy and the hourly dynamic simulations are conducted under Moroccan meteorological data. A comparative study between our numerical results and experimental results shows a good agreement and the Mean Relative Error (MRE) and the Root Mean Squared Error (RMSE) are 3.9% and 0.024 kg/kg, respectively. The energetic performance of the solar dryer components is investigated and the effect of some design and operation parameters on drying kinetic is presented. An environmental analysis is performed by focusing on the amount of carbon dioxide (CO 2) emissions due to the combustion at the auxiliary heater system. Results show that the integration of the solar collector into the dryer system leads to reduce the energy consumption by the auxiliary heater system and to avoid annually about 34% of CO 2 emissions. [ABSTRACT FROM AUTHOR]

Highlights • Predicting energy performance of a building integrated photovoltaic/thermal system. • Comparing the accuracy of various artificial neural network approaches. • Hybrid model is more accurate than the artificial neural network model. Abstract The objective of this work is to evaluate the feasibility of an optimized artificial neural network and particle swarm optimization for estimating the energetic performance of a building integrated photovoltaic/thermal system. A performance evaluation criterion is defined in this study to assess the overall performance of the considered system. Then, the mentioned methods are used to identify a relationship between the input and output parameters of the system. The performance evaluation criterion was taken as the essential output of the system, while the input parameters were the channel length, channel depth, channel width, and the air mass flow rate. The results revealed that the coefficient of determination for the training phase of the artificial neural network and particle swarm optimization-artificial neural network methods is respectively 0.9982 and 0.9997, while it is 0.9980 and 0.9997 for the testing phase. Moreover, the root mean square error for the training phase of the artificial neural network and particle swarm optimization-artificial neural network techniques was respectively 0.0462 and 0.0175, while it was 0.0493 and 0.0178 for the testing phase. Therefore, it was concluded that the particle swarm optimization-artificial neural network model could slightly perform a better performance compared to the conventional artificial neural network. [ABSTRACT FROM AUTHOR]

• Six members of FOX-7 family were designed based on the chemical reactivity of FOX-7 and the advantages of the D–A reaction. • Molecular structure, energetic performance, sensitivity, synthesis feasibility and mechanism were comprehensively described. • It helps to enrich the FOX-7 family and provides the theoretical support for further experimental synthesis. Herein, six members of FOX-7 family, i.e., PyFOX-7, APyFOX-7, NPyFOX-7, DAPyFOX-7, ANPyFOX-7, and DNPyFOX-7, were designed based on the Diels–Alder reaction. Their structures, sensitivity, energetic performance, together with synthesis route, feasibility and mechanism, were described by using the density function theory (DFT) method. Results show that NPyFOX-7 and DNPyFOX-7 are easier to synthesize, with Δ G ≠s of 115.21 and 114.71 kJ.mol−1, respectively, which are assigned to the inverse D−A reactions and undergo a stepwise mechanism. DNPyFOX-7 possesses comparable energetic performance with FOX-7 and RDX, and simultaneously shows lower sensitivity than RDX, which suggests it is a promising FOX-7 derivative and worth further experimental studies. This work helps to enrich the FOX-7 family and provides the theoretical support for further experimental synthesis. [ABSTRACT FROM AUTHOR]

DAP-4 (C 6 N 2 H 14) (NH 4) (ClO 4) 3 has been synthesized recently as an ammonium perchlorate-based molecular perovskite energetic material with higher stability and outstanding performances. In this study, rapid thermal cracking infrared spectroscopy is applied to study the thermal pyrolysis properties and combustion process of DAP-4. Under different temperatures and pressure with a heating rate of 1000 ℃·s−1, the gaseous products in the rapid pyrolysis process are mainly CO, CO 2 , H 2 CO, HCN, and HCl. Above 700ºC, the pressure affects the ratio of the gas products, but the temperature does not. Based on the relative ratio of the different gas products, a thermal pyrolysis mechanism was proposed. The heat of explosion (ΔH det), enthalpy of combustion(Δ c Hθ), and standard enthalpies of formation (Δ f Hθ) are determined to be –2527.39 kJ·mol−1, –2492.06 kJ·mol−1 and –483.96 kJ·mol−1, respectively. The self-catalytic heating time is 99.5 min, the temperature at the initial detection point is 280.1 ℃, and the maximum temperature rise rate is 49.1 ℃·min−1. The thermal safety experimental results showed that DAP-4 has a relatively good security performance. This study provides new insight into the mechanism of pyrolysis of DAP-4 as a potential energetic material. • Confirmed the mainly gaseous products are CO, CO 2 , H 2 CO, HCN, and HCl in DAP-4 rapid pyrolysis process. • The pressure affects the ratio of the gas products, but the temperature does not. • Proposed a thermal pyrolysis mechanism based on the relative ratio of the different gas products. • Obtained the security parameters of DAP-4. [ABSTRACT FROM AUTHOR]

This paper targets the identification of certain correlations between some energetic security indicators and some energetic performance indicators. The first part of the article refers to the importance of the concernes regarding the competitiveness of the energetic processes. The second part of the article presents the working methodology, also in this section we tryed defining two correlation coefficients and to present the econometric model and assessement algorithm. The third section of this article presents the results and the last section of the paper presents the main conclusions of the analysis.

Graphical abstract Highlights • The primitive and defective CL-20/TNT cocrystal models were established. • Molecular dynamics method was applied to predict the properties. • The properties of different models were calculated and compared. • The influences of crystal defects on properties of explosive were evaluated. • The article could provide some novel insights for properties estimation of explosives. Abstract In this work, the "perfect" and adulteration defective crystal models of hexanitrohexaazaisowurtzitane/2,4,6-trinitrotoluene (CL-20/TNT) cocrystal explosive were established. Molecular dynamics simulations were performed to predict the stability, sensitivity, energetic performance and mechanical properties of cocrystal models. The binding energy, trigger bond length distribution, interaction energy of trigger bond, cohesive energy density, detonation parameters and mechanical properties were calculated and compared. The influences of adulteration crystal defect on comprehensive properties of CL-20/TNT cocrystal explosive were explored and estimated. The results show that compared with primitive model, binding energies of defective models are decreased by 0.91–14.67%, i.e., the intermolecular interaction energy is decreased and stability is weakened. The maximum trigger bond length is increased by 0.33–4.36%, while the interaction energy of trigger bond is decreased by 1.33–12.27% and cohesive energy density is decreased by 0.45–11.24%, indicating that sensitivity is increased and safety is decreased. The density, detonation velocity and detonation pressure of defective models are decreased by 0.11–7.75%, 0.13–6.47%, 0.32–16.41%, respectively, illustrating that the power and energy density are decreased. Owing to the influence of crystal defect, tensile modulus is decreased by 0.128–5.683 GPa, bulk modulus is decreased by 0.109–3.409 GPa and shear modulus is decreased by 0.048–2.325 GPa, while Cauchy pressure is increased by 0.031–1.112 GPa, meaning that the rigidity, hardness and rupture strength are decreased, ductility is improved. Therefore, adulteration crystal defect has an undesirable influence on stability, sensitivity and energetic performance of CL-20/TNT cocrystal explosive. [ABSTRACT FROM AUTHOR]

The following paper is treating today's context, where the construction field is one of the major cause of pollution in most countries of the world. It actually has deep impacts on public health, soil and air. The following analysis is doing a comparison between international contracts frameworks to show what would be the best alternatives or which one is worth using for a green construction project. After developing how frameworks can be used for a sustainable construction they will be compared using relative weighting technique and the additive weighting technique. As a results of the analysis we will rank the best alternatives to find out the Consensusdoc and the American Institute of Architects provide satisfying frameworks for green buildings. In the end the consensudoc best fits today's green challenges as it give substantial guidance for establishing and achieving green measures. [ABSTRACT FROM AUTHOR]

In this work the analysis of the energetic performance of flat solar air heaters with simple cover operating in forced circulation regime was developed. For the analysis, the collector was modelled and simulated with Computational Dynamic Fluid technique, using the Fluent 6.3code. The collector performance versus the change of design parameters (length, air canal height) and the change of operating conditions (the incident solar radiation and air velocity)was analyzed. The graphic dependence and correlations of hourly and daily collector thermal efficiency, of exit air temperature as function of the collector length, of the air canal height, of the air velocity and of solar incident radiation were carried out. The found correlations are useful for the designers of solar air heaters as tools to improve the design in function of desired aim, either higher exit air temperature, higher efficiency or any combination of these parameters. [ABSTRACT FROM AUTHOR]

This article presents an analysis of the feasibility of R454C and R455A, two new low global warming potential (GWP of 148) refrigerants, in vapor compression refrigeration systems as alternatives to R404A for warm countries. R454C and R455A can be the most viable low GWP options to perform a direct replacement of R404A because of the similar characteristics. They only present meaningful differences in flammability, critical temperature, temperature glide and vapor density. The analysis is based on an experimental comparison of R404A with R454C and R455A, using a fully instrumented experimental setup equipped with Internal Heat Exchanger (IHX) at condensation temperatures that represent operating conditions of warm countries. The experimental results show that cooling capacity of the replacements is slightly lower than R404A, being the Coefficient of Performance (COP) of the new mixtures 10–15% higher than that of R404A, especially at higher condensation temperatures. The results also show that the adoption of an IHX is not recommended with the alternatives due to the discharge temperature increase and the low energy performance benefit. [ABSTRACT FROM AUTHOR]

In this work, an energetic composite fiber, in which 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) nanoparticles intimately incorporated with a nitrocellulose/glycidyl azide polymer (NC/GAP) fiber, was prepared by the electrospinning method. The morphology and structure of the nanofiber was characterized by scanning electron microscopy (SEM), energy dispersive X-Ray (EDX), fourier transform infrared spectroscopy (IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Brunauer−Emmett−Teller (BET). The nanofibers possessed a three-dimensional (3D) net structure and a large specific surface area. Thermal analysis, energetic performance, and sensitivities were investigated, and they were compared with NC/GAP and LLM-105 nanoparticles. The NC/GAP/nano-LLM-105 nanofibers show higher decomposition rates and lower decomposition temperatures. The NC/GAP/nano-LLM-105 decomposed to CO2, CO, H2O, N2O, and a few NO, -CH2O-, and -CH- fragments, in the thermal-infrared spectrometry online (TG-IR) measurement. The NC/GAP/nano-LLM-105 nanofibers demonstrated a higher standard specific impulse (Isp), a higher combustion chamber temperature (Tc), and a higher specialty height (H50). The introduction of nano-LLM-105 in the NC/GAP matrix results in an improvement in energetic performance and safety.

Current concerns focus on the need to reduce energy consumption in construction and over the lifespan of buildings. A major objective is to create affordable housing. However, reducing the energy needs of the present without harming the needs of future generations remains difficult to put into practice, especially at the level of habitats in arid zones. In this research, a housing design assistance process for building designers is proposed, with the aim of converging towards a global optimum for the correlation and integration of vernacular devices and strategies in an optimized way. This will allow the integration of energy performance indicators and user comfort, in order to ultimately optimize, for this case study, the morphogenesis of residential buildings based on the morphological structure of a proposed building in Biskra, Algeria. This last developed process is articulated on various combinations distinguished for the case of the integration of devices and strategies, which allow maximum energy saving while ensuring the comfort of the occupants. As part of this research, this integration constituted a major challenge and made it possible to achieve a reduction in energy ratio of up to 25.11% compared to the standard building and the objectives of the research.

This paper presents a comprehensive study that aims to assess the energetic performances of a solar hot water collective system under a realistic load consumption profile in Morocco. The case study which has been considered in this work is a residential building located in Fez city. Several parameters are involved into the performance assessment of the collective system. Hence, it was essential to identify the parameters on which we will act in order to carry out the parametric study. In fact, the technology of evacuated tube collectors (ETC) with heat pipes were selected as a fixed study parameter, while a set of other indicators were investigated contributing to the collective hot water system design and optimization, such as the solar collector panel total area, the connecting methods between the collector’s field which could be serial, parallel or mixed connection, the collective hot water storing volume configurations in addition to the intrinsic optical efficiencies of the world’s manufacturers solar collectors. In order to achieve the assessment of the energetic performances of the collective system, four parametric studies were described and carried out to ensure its design and optimization during the dynamic mode operation. The most relevant findings from this research paper are presented as follows. Incrementing the collector’s field area to 120 m 2 optimizes the thermal efficiency of the collective system, and the hydraulic booster consumption is reduced. Besides, it would be advantageous to use a total area of 80 m 2 to satisfy the hot water need demand over the four seasons, since the overall collective system thermal efficiency remain above 60%. Moreover, is was possible to ensure a seasonal solar fraction which is greater than 50% by connecting a collective storage tank with a volume of 1500 l and a solar collector panel with an area of 100 m 2 . Last but not least, the effect of the row’s number as well as the number of collectors connected per row on the overall collective system’s solar fraction was also investigated through this study. [ABSTRACT FROM AUTHOR]

Bifunctional tetrazole-carboxylates, 5-( n-pyridyl)tetrazole-2-isopropionic acid (denoted as Hn-pytzipa, n = 2, 3) have been selected to be reacted with CdCl·2.5 HO under solvothermal conditions, [Cd(2-pytzipa)(MeOH)Cl] ( 1) and [Cd(3-pytzipa)] ( 2) were obtained. In compound 1, 2-pytzipa is a pentadentate ligand to bridge adjacent Cd(II) centers to generate a fascinating 3D dinodal 4-connected, 5-connected net with point symbol of (4·8)(4·6·7). In 2, each 3-pytzipa bridges three Cd(II) atoms in a μ -COO syn-anti mode to generate a fascinating 3D one-nodal 6-connected net with point symbol of (4·5·6·7). Photoluminescence properties of compounds 1 and 2 in the solid state show enhanced ligand centered emission. Furthermore, thermogravimetric-differential (TG-DTG) and differential scanning calorimetry (DSC) were used to evaluate the thermal decomposition behavior of compounds 1 and 2, showing that the decomposition process of compound 2 is much more intense than that of compound 1. The thermal parameters (∆S, ∆H and ∆G) of the decomposition of compound 2 were calculated, as well. [ABSTRACT FROM AUTHOR]

This article first gives a brief review of thermal engines designed for terrestrial transportation since the 1900s. We then outline the main developments in the state of the art and knowledge about internal combustion engines, focusing on the increasingly stringent pollution constraints imposed since the 1990s. The general concept of high-energy performance machines is analyzed from the energy, exergy, and public health point of view and illustrated with typical examples of clean energy production and zero emissions. Whereas the energy analysis revealed high potential of waste heat recovery from both exhaust and cooling system, the exergetic analysis revealed much higher recovery potential from exhaust gases. The exergy content of exhaust gases was observed to be within the range from 10.4% to 20.2% of the fuel energy. The cooling exergy is within the range from 1.2% to 3.4% of the fuel energy. The article concludes with some perspectives for the emergence of an economic model that could be applied to land-based transport systems in the framework of energy transition by 2030. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Recently, energetic coordination polymers (ECPs) have attracted much attention with the reinforced structure and enhanced energetic performance. In the fields of energetic materials (EMs), azido-based EMs always possess excellent detonation properties with high sensitivities. To develop novel EMs with high energy and low sensitivity simultaneously, in this study, a new azido-based ECP [Ni 3 (TTA) 4 (N 3) 2 ·2MeOH] n 1 (HTTA ​= ​1 H -tetrazol-1-ylacetic acid) featuring in a 2D network structure were obtained though nanoarchitectonics and a simple solvothermal method. The single crystal X -ray diffraction analysis indicates that 1 consists of Ni2+ centers and nitrogen-rich TTA– ligands with sensitive azido ions embedded in the 2D plane. Moreover, strong hydrogen bonds between carboxyl groups and MeOH molecules can further reinforce the structure and improve the stabilities. The decomposition temperature (T dec), impact sensitivity (IS), and the friction sensitivity (FS) of 1 is 251 ​°C, >40 ​J, and 80 ​N, respectively, showing significant advantages in contrast with the reported azido-based ECPs. The calculated heat of detonation (ΔH det) value is 3.270 ​kJ ​g−1, which is higher than that of TNT (ΔH det ​= ​1.220 ​kJ ​g−1). According to the above analysis, compound 1 has promise to serve as EMs because of its high stability and excellent energetic performance. The sensitive azido ions dispersed in the 2D network to improve the energetic performance and maintain the stabilities of ECPs with high heat of detonation (3.270 ​kJ ​g−1). [Display omitted] • A sensitive azido-based energetic coordination polymer (ECP) [Ni 3 (TTA) 4 (N 3) 2 ·2MeOH] n 1 with reliable stabilities was successfully prepared. • The sensitive azido ions were orderly dispersed in the 2D network to improve the energetic performance. • Compound 1 has the higher heat of detonation compared with the TNT. [ABSTRACT FROM AUTHOR]

The use of the minimum energy to maintain the indoor thermal comfort of the large-space public building is always a challenging task due to the complex outdoor environment and indoor requirements. The lack of monitoring data and effective approaches limits the understanding of building thermal and energetic performance. This paper thus proposes a hybrid machine learning model based on factor generators and an optimization approach to address this research topic, aiming to provide the essential guide for future retrofit and design of large-space public buildings. The four machine learning (ML)-based factor generators are compared using the one-year monitoring data of building facility and indoor thermal management, where the high-performance multilayer perceptron neural networks (MLPNN) model is chosen as the data-driven method to generate the input data as the parent or intermediate populations in the GA optimization algorithm. Such a hybrid machine learning model can solve the multi-objective functions of thermal comfort and carbon emissions. The optimization results demonstrate that this model can achieve a maximum 29% improvement for thermal comfort and a reduction of 386.9 kg CO 2 (11.06%) for carbon emissions in comparisons with the human-based management. Moreover, such hybrid machine learning model exhibits tolerance for moderate deficit in one objective. Therefore, the optimal thermal comfort and carbon emissions of large-space public buildings are achieved and thus contributing to the carbon neutrality in the building sector. • The multi-objective problem of thermal comfort and carbon emission is addressed. • The MLPNN models perform well according to the prediction evaluation criteria. • A 29% thermal comfort improvement and the 386.9 kg CO 2 reduction are achieved. • The new model reduces the wasteful energy from human-based decision-making. • The hybrid machine learning model can tolerate the moderate deficit. [ABSTRACT FROM AUTHOR]

Recent progress in high-energy metal–organic frameworks (HE-MOFs), not only a burgeoning branch of growing interest in energetic materials but also a particular class of metal–organic frameworks (MOFs), is covered in this review. HE-MOFs, based on various nitrogen-rich energetic ligands, may serve as an effective approach for systematically studying the energetic-sensitive-structural relationships and guiding the future design of new generation high-energy-density materials (HEDMs) because of their various advantages, including controllable structures, various modifiable functionalities, high density, remarkable heats of detonation, insensitivity, good thermal stability and favorable mechanical hardness. In the review, an inductive overview of the development and outlook in the field of HEDMs, particularly those with one-, two- and three-dimensional (1D–3D) architectures, are presented. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations studies are carried out on hydroxyl terminated polyethers that are useful in energetic polymeric binder applications. Energetic polymers derived from oxetanes with heterocyclic side chains with different energetic substituents are designed and simulated under the ensembles of constant particle number, pressure, temperature (NPT) and constant particle number, volume, temperature (NVT). Specific volume of different amorphous polymeric models is predicted using NPT-MD simulations as a function of temperature. Plots of specific volume versus temperature exhibited a characteristic change in slope when amorphous systems change from glassy to rubbery state. Several material properties such as Young's, shear, and bulk modulus, Poisson's ratio, etc. are predicted from equilibrated structures and established the structure–property relations among designed polymers. Energetic performance parameters of these polymers are calculated and results reveal that the performance of the designed polymers is comparable to the benchmark energetic polymers like polyNIMMO, polyAMMO and polyBAMO. Overall, it is worthy remark that this molecular simulations study on novel energetic polyethers provides a good guidance on mastering the design principles and allows us to design novel polymers of tailored properties. [ABSTRACT FROM AUTHOR]

The energetic performance of landfill biogas (LB) and biodigester biogas (BB) from municipal waste was examined in consumption tests. These tests were performed in situ at a gas generation plant associated with a landfill facility in Madrid (Spain) and following the standard UNE-EN 30-2-1 (1999). The jets of a domestic cooker commonly used for natural gas (NG) or liquefied petroleum gas (LPG) were modified to operate with the biogases produced at the facility. The working pressures best suited to the tested gases, i.e., to avoid flashback and flame lift, and to ensure the stability and correct functioning of the flame during combustion, were determined by trial and error. Both biogases returned optimum energetic performance for the transfer of heat to water in a metallic recipient (as required by the above standard) at a supply pressure of 10 mbar. Domestic cookers are normally supplied with NG at a pressure of 20 mbar, at which pressure the energetic performance of G20 reference gas was higher than that of both biogases (52.84% compared to 38.06% and 49.77% respectively). Data concerning these issues involving also unexplored feedstock are required for the correct conversions of domestic cookers in order to avoid risks of serious personal injuries or property damages. [ABSTRACT FROM AUTHOR]