A new criterion of coal burst proneness based on the residual elastic energy index

To evaluate the coal burst proneness more precisely,a new energy criterion namely the residual elastic energy index was proposed.This study begins by performing the single-cyclic loading-unloading uniaxial compression tests with five pre-peak unloading stress levels to explore the energy storage characteristics of coal.Five types of coals from different mines were tested,and the instantaneous destruction process of the coal specimens under compression loading was recorded using a high speed camera.The results showed a linear relationship between the elastic strain energy density and input energy density,which confirms the linear energy storage law of coal.Based on this linear energy storage law,the peak elastic strain energy density of each coal specimen was obtained precisely.Subsequently,a new energy criterion of coal burst proneness was established,which was called the residual elastic energy index(defined as the difference between the peak elastic strain energy density and post peak failure energy density).Considering the destruction process and actual failure characteristics of coal specimens,the accuracy of evaluating coal burst proneness based on the residual elastic energy index was examined.The results indicated that the residual elastic energy index enables reliable and precise evaluations of the coal burst proneness.

Theoretical verification of the rationality of strain energy storage index as rockburst criterion based on linear energy storage law

The rationality of using strain energy storage index(Wet)for evaluating rockburst proneness was theoretically verified based on linear energy storage(LES)law in this study.The LES law is defined as the linear relationship between the elastic strain energy stored inside the solid material and the input strain energy during loading.It is used to determine the elastic strain energy and dissipated strain energy of rock specimens at various loading/unloading stress levels.The results showed that the Wetvalue obtained from experiments was close to the corresponding theoretical one from the LES law.Furthermore,with an increase in the loading/unloading stress level,the ratio of elastic strain energy to dissipated strain energy converged to the peak-strength strain energy storage index(Wp et).This index is stable and can better reflect the relative magnitudes of the stored energy and the dissipated energy of rocks at the whole pre-peak stage than the strain energy storage index.The peak-strength strain energy storage index can replace the conventional strain energy storage index as a new index for evaluating rockburst proneness.

Experiments on rockburst proneness of pre-heated granite at different temperatures: Insights from energy storage, dissipation and surplus

Many underground engineering projects show that rockburst can occur in rocks at great depth and high temperature, and temperature is a critical factor affecting the intensity of rockburst. In general, temperature can affect the energy storage, dissipation, and surplus in rock. To explore the influence of temperature on the energy storage and dissipation characteristics and rockburst proneness, the present study has carried out a range of the uniaxial compression(UC) and single-cyclic loading-unloading uniaxial compression(SCLUC) tests on pre-heated granite specimens at 20℃-700℃. The results demonstrate that the rockburst proneness of pre-heated granite initially increases and subsequently decreases with the increase of temperature. The temperature of 300℃ has been found to be the threshold for rockburst proneness. Meanwhile, it is found that the elastic strain energy density increases linearly with the total input strain energy density for the pre-heated granites, confirming that the linear energy property of granite has not been altered by temperature. According to this inherent property, the peak elastic strain energy of pre-heated granites can be calculated accurately. On this basis, utilising the residual elastic energy index, the rockburst proneness of pre-heated granite can be determined quantitatively. The obtained results from high to low are: 317.9 k J/m^(3)(300℃), 264.1 k J/m^(3)(100℃), 260.6 k J/m^(3)(20℃), 235.5 k J/m^(3)(500℃), 158.9 k J/m^(3)(700℃), which are consistent with the intensity of actual rockburst for specimens. In addition, the relationship between temperature and energy storage capacity(ESC) of granite was discussed, revealing that high temperature impairs ESC of rocks, which is essential for reducing the rockburst proneness. This study provides some new insights into the rockburst proneness evaluation in high-temperature rock engineering.

Development of Wi-Fi Based Home Energy Monitoring System for Green Internet of Things

Green Internet of things （loT） has been heralded as the ＂next big thing＂ waiting to be realized in energy-efficient ubiquitous computing. Green IoT revolves around increased machine-to-machine communications and encompasses energy-efficient wireless embedded sensors and actuators that assist in monitoring and controlling home appliances. Energy efficiency in home applications can be achieved by better monitoring of the specific energy consumption by the appliances. There are many wireless standards that can be adopted for the design of such embedded devices in loT. These communication technologies cater to different requirements and are classified as the short-range and long-range ones. To select the best communication method, this paper surveys various loT communication technologies and discusses the advantages and disadvantages to develop an energy monitoring system. An IoT device based on the Wi-Fi technology system is developed and tested for usage in the home energy monitoring environment. The performance of this system is then evaluated by the measurement of power consumption metrics. In the efficient deep-sleep mode, the system saves up to 0.3 W per cycle with an average power dissipation of less than 0.1 W/s.

Dual-radiation-chamber coordinated overall energy efficiency scheduling solution for ethylene cracking process regarding multi-parameter setting and multi-flow allocation

Ethylene cracking process is the core production process in ethylene industry,and is paid more attention to reduce high energy consumption.Because of the interdependent relationships between multi-flow allocation and multi-parameter setting in cracking process,it is difficult to find the overall energy efficiency scheduling for the purpose of saving energy.The traditional scheduling solutions with optimal economic benefit are not applicable for energy efficiency scheduling issue due to the neglecting of recycle and lost energy,as well as critical operation parameters as coil outlet pressure(COP)and dilution ratio.In addition,the scheduling solutions mostly regard each cracking furnace as an elementary unit,regardless of the coordinated operation of internal dual radiation chambers(DRC).Therefore,to improve energy utilization and production operation,a novel energy efficiency scheduling solution for ethylene cracking process is proposed in this paper.Specifically,steam heat recycle and exhaust heat loss are considered in cracking process based on 6 types of extreme learning machine(ELM)based cracking models incorporating DRC operation and three operation parameters as coil outlet temperature(COT),COP,and dilution ratio according to semi-mechanism analysis.Then to provide long-term decision-making basis for energy efficiency scheduling,overall energy efficiency indexes,including overall output per unit net energy input(OONE),output-input ratio per unit net energy input(ORNE),exhaust gas heat loss ratio(EGHL),are designed based on input-output analysis in terms of material and energy flows.Finally,a multiobjective evolutionary algorithm based on decomposition(MOEA/D)is employed to solve the formulated multi-objective mixed-integer nonlinear programming(MOMINLP)model.The validities of the proposed scheduling solution are illustrated through a case study.The scheduling results demonstrate that an optimal balance between multi-flow allocation,multi-parameter setting,and DRC coordinated operation is reached,which achieves 3.37%and 2.63%decreases in net energy input for same product output and conversion ratio,as well as the 1.56%decrease in energy loss ratio.

Effects of Seed Dressing with Microbial Inoculum on Nutrient Composition and Biological Yield of Silage Corn

[Objectives]This study was conducted to understand the effects of microbial inocula on the biological yield and nutritional components of corn.[Methods]Silage corn varieties suitable for planting in Hebei Province were selected,and set with an experimental group and a control check group each.Meanwhile,at the late stage of milk ripening of silage corn growth cycle,the nutritional components and indexes of silage corn were determined and analyzed by a near-infrared analyzer and the NIRS technique.Meanwhile,the biological yield of silage corn was determined at the maturation stage of its growth period,aiming at comprehensively evaluating the regulation effects of the microbial inoculum tested on silage corn from the aspects of basic nutritional components,mineral element contents,energy and related indexes of corn,combined with agronomic characters and biological yield.[Results]The microbial inoculum improved the biological yield and nutritional indexes of silage corn,and had a positive regulation effect on the growth of silage corn.[Conclusions]The results of this study provide a theoretical basis for popularizing the planting methods and cultivation methods of silage corn with high yield and high quality.

Experimental Study on the Mechanical Parameters Relating to the Impact Tendency of Coal Sample

Coal burst remains one of the gravest safety risks that will be encountered in mining in the future, because the stress conditions will become more complex as mining depths increase. Various influencing elements exist, and varied geological and mining circumstances might result in diverse coal burst phenomena. The impact propensity of coal has variations as a result of the distinct physical and mechanical qualities of each. To identify the impact propensity of coal and then understand the rules of coal burst occurrence, laboratory tests can be conducted to identify the physical and mechanical parameters affecting coal samples. The mechanical properties, energy absorption, and energy dissipation characteristics of coal samples were examined experimentally in this paper using coal samples that were taken from the mine. On the basis of the evaluation of the impact inclination parameters for four fundamental coal samples, novel impact inclination indicators and the relationship between the fractures in the coal sample and the impact inclination parameters were discussed. The following are the key conclusions: 1) On-site samples of No. 15 coal from the Qi yuan Coal Mine were taken (15 s) and processed in accordance with the guidelines for the coal specimen impact inclination test. The accuracy of the specimen was sufficient for the test. 2) Analysis is done on the mechanical relevance and calculation techniques of the four fundamental coal sample impact tendency characteristics, dynamic failure time (DT), elastic strain energy index (WET), impact energy index (KE), as well as uniaxial compressive strength (RC). 3) Regarding the rock burst danger of rock samples, the potential use of the ratio of pre-peak and post- peak deformation modulus to Kλ and the residual elastic strain energy index CEF as the impact propensity indices of coal samples are discussed. It is possible to utilize two new impact propensity indices to evaluate the impact propensity of coal samples, according to test results that reveal a linear correlation between two new impact inclination indexes and four fundamental impact tendency indexes. 4) The statistical analysis of the crack ratio with the four impact propensity indicators after coal specimen failure, and the correlation among the crack ratio with the indicators, are both done. The findings indicate that the four impact propensity indicators have a linear relationship with the crack ratio of the coal sample surface cracks.

Experimental Study on the Mechanical Parameters Relating to the Impact Tendency of Coal Sample

Coal burst remains one of the gravest safety risks that will be encountered in mining in the future, because the stress conditions will become more complex as mining depths increase. Various influencing elements exist, and varied geological and mining circumstances might result in diverse coal burst phenomena. The impact propensity of coal has variations as a result of the distinct physical and mechanical qualities of each. To identify the impact propensity of coal and then understand the rules of coal burst occurrence, laboratory tests can be conducted to identify the physical and mechanical parameters affecting coal samples. The mechanical properties, energy absorption, and energy dissipation characteristics of coal samples were examined experimentally in this paper using coal samples that were taken from the mine. On the basis of the evaluation of the impact inclination parameters for four fundamental coal samples, novel impact inclination indicators and the relationship between the fractures in the coal sample and the impact inclination parameters were discussed. The following are the key conclusions: 1) On-site samples of No. 15 coal from the Qi yuan Coal Mine were taken (15 s) and processed in accordance with the guidelines for the coal specimen impact inclination test. The accuracy of the specimen was sufficient for the test. 2) Analysis is done on the mechanical relevance and calculation techniques of the four fundamental coal sample impact tendency characteristics, dynamic failure time (DT), elastic strain energy index (WET), impact energy index (KE), as well as uniaxial compressive strength (RC). 3) Regarding the rock burst danger of rock samples, the potential use of the ratio of pre-peak and post- peak deformation modulus to Kλ and the residual elastic strain energy index CEF as the impact propensity indices of coal samples are discussed. It is possible to utilize two new impact propensity indices to evaluate the impact propensity of coal samples, according to test results that reveal a linear correlation between two new impact inclination indexes and four fundamental impact tendency indexes. 4) The statistical analysis of the crack ratio with the four impact propensity indicators after coal specimen failure, and the correlation among the crack ratio with the indicators, are both done. The findings indicate that the four impact propensity indicators have a linear relationship with the crack ratio of the coal sample surface cracks.

Is pass‑through of the exchange rate to restaurant and hotel prices asymmetric in the US?Role of monetary policy uncertainty

This study examines the exchange rate pass-through to the United States(US)restaurant and hotel prices by incorporating the effect of monetary policy uncertainty over the period 2001:M12 to 2019:M01.Using the nonlinear autoregressive distributed lag(NARDL)model,empirical evidence indicates asymmetric pass-through of exchange rate and monetary policy uncertainty.Moreover,a stronger pass-through effect is observed during depreciation and a negative shock in monetary policy uncertainty,corroborating asymmetric pass-through predictions.Our results further show that a positive shock in energy prices leads to an increase in restaurant and hotel prices.Furthermore,asymmetric causality indicates that a positive shock in the exchange rate causes a positive shock to restaurant and hotel prices.We found feedback causal effects between positive and negative shocks in monetary policy uncertainty and positive and negative shocks in the exchange rate.Additionally,we detected a one-way asymmetric causality,flowing from a positive(negative)shock to a positive(negative)shock in energy prices.Therefore,these findings provide insights for policymakers to achieve low and stable prices in the US restaurant and hotel industry through sound monetary policy formulations.Highlights.The drivers of restaurant and hotel business in tourism destinations are examined.There is asymmetric pass-through of exchange rate and monetary policy uncertainty.A stronger pass-through is observed during appreciation and a negative shock to monetary policy uncertainty.There is asymmetric causality from positive shock in exchange rate to postive shock in restaurant and hotel prices.

海上运输的脱碳:土耳其船队的案例研究

Climate change and global warming are among the most severe threats to the global ecosystem,caused by greenhouse gas emissions.Therefore,all industries that cause environmental emissions should collaborate in the struggle against climate change.In this context,the International Maritime Organization(IMO)approved the initial greenhouse gas strategy at the MEPC 72 session in April 2018 to achieve targets for 2050.With this strategy,the IMO aims to create and improve new regulations that can enhance energy efficiency to achieve their short-term,midterm,and long-term goals.In this study,one of the novel terms,energy efficiency existing ship index(EEXI)values,has been calculated for the Turkish fleet to guide the maritime sector.The Turkish fleet in the study refers to the Turkish-owned vessels both sailing with a national or international flag.In accordance with this regulation,the number of Turkish fleets that were identified as either above or below the IMO reference lines has been determined.Additionally,EEXI values have been recalculated using the engine power limitation(EPL)method for ships that exceed the required limits,and the success rate of this method has been estimated.As a result,the application of EPL increased the number of ships below the Phase 2 reference line from 15.6%to 53.1%.To the best of our knowledge,this research,which has been carried out on all Turkish-owned ships,is the first study intended to serve as a guide for other ship owners in the global maritime industry regarding energy efficiency management.

Peak-strength strain energy storage index for evaluating coal burst liability based on the linear energy storage law

The strain energy storage index WET was widely used to evaluate coal burst liability,but the scientific evidence for selecting the unloading stress level interval(around 80%of peak strength)remains lacking,and WET can not reflect the energy storage and dissipation ratio(ESD ratio)of the whole pre-peak stage for coal materials.In this study,these two key problems in WET calculation and application were solved based on the linear energy storage(LES)law.The LES law was defined as the linear relationship between the elastic strain energy and input strain energy for solid material during loading.Using the LES law,the elastic strain energy and dissipated strain energy of at 10 types of coals were calculated precisely,and ideal ESD ratio and general ESD ratio at any stress level will be obtained subsequently.The results also show that WET is extremely close to the ideal and general ESD ratio,which proves that the selecting stress level of WET calculation is scientific and reasonable.Furthermore,the general ESD ratio converges to the peak ESD ratio(namely peak strain energy storage index WET P)as stress level increases.Compared with WET,Wp ET not only reflects the ESD ratio of coal materials over the whole pre-peak loading stage,but also exhibits excellent stability.Consequently,Wp ET is suggested as a new evaluation index of coal burst liability.

IMPROVED COVARIANCE DRIVEN BLIND SUBSPACE IDENTIFICATION METHOD

An improved covariance driven subspace identification method is presented to identify the weakly excited modes. In this method, the traditional Hankel matrix is replaced by a reformed one to enhance the identifiability of weak characteristics. The robustness of eigenparameter estimation to noise contamination is reinforced by the improved Hankel matrix, in combination with component energy index （CEI） which indicates the vibration intensity of signal components, an alternative stabilization diagram is adopted to effectively separate spurious and physical modes. Simulation of a vibration system of multiple-degree-of-freedom and experiment of a frame structure subject to wind excitation are presented to demonstrate the improvement of the proposed blind method. The performance of this blind method is assessed in terms of its capability in extracting the weak modes as well as the accuracy of estimated parameters. The results have shown that the proposed blind method gives a better estimation of the weak modes from response signals of small signal to noise ratio （SNR）and gives a reliable separation of spurious and physical estimates.

孟加拉国内河船能效设计指数的进展情况

More than 10000 different types of ship ply the waters of Bangladesh all year round,but the performance of these ships in terms of CO2 emission is not known and regulations related to energy efficiency of inland waterway ships remain nonexistent.This paper attempts to assess the present situation of inland class vessels in terms of Energy Efficiency Design Index(EEDI).With the use of a developed database of inland vessels in Bangladesh,EEDI reference lines for different types of inland vessels in Bangladesh were established and then compared with those of other countries.The present EEDI of existing inland vessels was investigated.Results indicate that most of the existing vessels do not meet the current EEDI baseline.Hence,new guidelines are necessary to achieve EEDI compliance in the near future.Some recommendations were proposed for improving CO2 emissions,with the socioeconomic and technical factors in Bangladesh taken into consideration.

Energy flow in negative index materials

Prom Maxwell's equations, we compute the speed and the direction of propagation of active power refracted from air into a negative index material. We prove, both analytically and numerically that the power may refract positively even if phase fronts refract negatively. Considerations on the usage of ray optics in problems involving negative index materials are drawn.

Damage detection in beam-like structures using static shear energy redistribution

In this study,a static shear energy algorithm is presented for the damage assessment of beam-like structures.According to the energy release principle,the strain energy of a damaged element suddenly changes when structural damage occurs.Therefore,the change in the static shear energy is employed to determine the damage locations in beam-like structures.The static shear energy is derived from the spectral factorization of the elementary stiffness matrix and structural deflection variation.The advantage of using shear energy as opposed to total energy is that only a few deflection data points of the beam structure are required during the process of damage identification.Another advantage of the proposed approach is that damage detection can be performed without establishing a structural finiteelement model in advance.The proposed technique is first validated using a numerical example with single,multiple,and adjacent damage scenarios.A channel steel beam and rectangular concrete beam are employed as experimental cases to further verify the proposed approach.The results of the simulation and experiment examples indicate that the proposed algorithm provides a simple and effective method for defect localization in beam-like structures.

Evaluation of asphalt mixture behavior incorporating warm mix additives and reclaimed asphalt pavement

Incorporation of warm mix asphalt （WMA） and reclaimed asphalt pavement （RAP） has benefited the asphalt industry in many ways such as reducing the demand for virgin materials, lowering energy requirement during the asphalt production and construction, in addition to reducing greenhouse-gas emissions. This study evaluated the effects of Evotherm and RH-WMA and RAP on mixtures＇ behavior in terms of the compaction energy index （CEI）, indirect tensile strength （ITS） and resilient modulus. The results showed that warm mix additives reduced the CEI, ITS and resilient modulus; while RAP increased the corresponding values. Statistical analysis showed that mixtures incorporating Evotherm and RAP had significant effects on CEI, while the effects of RH-WMA on the corresponding value were found to be statistically insignificant. General Linear Model showed that Evotherm, RAP and RH-WMA exhibited no significant effects on the ITS and resilient modulus. The one-way analysis of variance showed that Evotherm influenced mixture behavior significantly, while RAP and RH-WMA effects were found to be statistically insignificant. Regression equations with high accuracy levels were proposed to predict CEI, ITS and resilient modulus with respect to modification of mixture variables such as mix constituents （Evotherm, RH-WMA, and RAP） and compaction temperature.

Atlas of heating:Identifying regional climate-dependent heat demands in residential buildings of Iran

Due to different latitudes and variation of altitude in geographical areas in Iran,the climatic conditions of Iran are such that the variations of the heating degree-days(HDD)are in a broad range of 60 to 3000 for residential buildings in different climatic regions.In addition,in many cases,the building design and construction processes follow patterns which do not necessarily meet national energy requirements and standards.Based on these two reasons,it is essential to identify the current status of energy consumption indicators in residential buildings.That way,it gets more convenient to adopt new strategies to improve the current state of energy consumption of buildings.In this study,heating energy consumption indices of residential buildings is investigated.Using the combination of the results of statistical data analysis,questionnaires,filled in for 500 buildings,and a reference building simulation in different climates of Iran,the heating atlas of residential buildings was prepared.According to the results,the average heating energy index(HE1)of buildings in Iran can be less than 1 to more than 41.3(m^(3)(N.G)/(m^(2)-yr))depending on climatic conditions and building design and construction quality.However,in the coldest center of province,the average of this index is 26.3(m^(3)(N.G)/(m^(2)-yr))in the hottest one that is equal 2.2.The variations of the thermal base load(supply of hot water)varied from less than 13.12 to more than 378.84(m^(3)(N.G)/(person-yr)).In provincial capitals,the lowest thermal base load index(TBLI)of buildings is 24.78 and the highest is 226.49(m^(3)(N.G)/(person-yr)).In this paper,beside charts and tables,results of heating energy consumption indices are also presented in the form of graphical atlases,i.e.color contour plots,to deliver a better picture of the whole country.

Thermo-oxidative degradation of Nylon 1010 films:Colorimetric evaluation and its correlation with material properties

The thermo-oxidative aging behaviors of Nylon 1010 films were studied by various analytical methods,such as measuring the chromaticity,relative viscosity,carbonyl index,UV absorbance at 280 nm and elongation at break of the aged films.The thermo-oxidative aging plots of the results obtained via these various methods at different temperatures are subjected to the time-temperature superposition analysis,which are found to be well superposed.The b＊ values are used as X axis and the other results,i.e.,relative viscosity,carbonyl index,UV absorbance at 280 nm and elongation at break,are used as V axis,respectively.The relationship between the b values and the other results is obtained,from which we can derive the changes of physical and chemical properties at different b＊ values.Since the b＊ values can be quickly determined by using a portable spectrophotometer,the on-line evaluation of the thermo-oxidative aging of Nylon 1010 can be realized.