Despite the significant advancements in geomodelling techniques over the past few decades, it is still quite challenging to obtain accurate assessments of hydraulic fracture propagation. This work investigates the effect of fluid leak-off in a dual-porosity system on the hydraulic fracture propagation geometry, which, in turn, affects hydrocarbon recovery from tight and unconventional reservoirs. Fracture propagation within tight reservoirs was analyzed using the Pseudo Three-Dimensional-Carter II model for single- (P3D-C) and dual-porosity systems (P3D-C-DP). Previous studies have accounted for leak-off in single-porosity models; however, studies within dual-porosity systems are still quite limited. We present a novel approach to coupling fluid leak-off in a dual-porosity system along with a fracture-height growth mechanism. Our findings provide important insights into the complexities within hydraulic fracturing treatment design using our new and pragmatic modeling approach. The simu... [more]

The main objective of this research is to assess the impact of energy certificate ratings (EPCs) on the value per m2 of Portuguese housing sales. Data from 289 Portuguese municipalities between 2014 and 2019, analysed with a fixed effects panel and method of moments quantile regression, were used. EPCs with high energy efficiency ratings (e.g., A+, A, B, and B-) are used as a proxy for dwellings with “green” or “environmentally friendly” certificates. On the other hand, ratings with a low energy efficiency (e.g., C, D, E, and F) are used as a proxy for dwellings with “non-green” or “not environmentally friendly” certificates. The results support that EPCs associated with green housing increase the value per m2 of housing sales, and those associated with non-green housing decrease the sales value. It was also found that municipal GDP, tax/financial incentive policies for energy efficiency, and the number of completed dwellings in new constructions for family housing will increase sales... [more]

This paper introduces a fiber generator using PVDF with a high-performance lead-free piezoelectric ceramic as filler. The piezoelectric ceramic filler was Ba0.84Ca0.16Ti0.90Zr0.10O3 + CuO 0.25 wt% (BCTZC0.25) sintered at 1550 °C. The BCTZC0.25 has an improved high-energy conversion constant (d33 × g33). The fiber generator made of PVDF/BCTZC0.25 composite fiber showed 1.6 times better piezoelectric power generation performance compared to a pure PVDF fiber generator. The PVDF/BCTZC0.25 fiber generator produced an output voltage of 1.9 V at 4 Hz. Hence, we successfully demonstrated that a composite fiber generator that uses piezoelectric ceramics which are harmless to the human body can outperform a pure PVDF fiber generator.

In order to ensure the full heat dissipation of heat exchangers, the opening of the grille should be large, which increases the wind drag of the whole vehicle. Most of the research on the grille only focuses on its impact on the heat dissipation of the engine compartment; there is little research on its influence on the performance of the thermal management system, because it is difficult to solve the real-time data interaction of different dimensional models. So we established the 1D and 3D strong coupling model. The biggest difference from other 1D and 3D coupling models is that we can use the interfaces reserved by the two kinds of software to realize real-time data interaction, and simultaneously analyze the 1D thermal management performance and 3D flow field and temperature field of the engine components. The coupling model is used to study three heat balance conditions. The results show that the heat-sinking capability of the cooling system is the worst under the climbing conditi... [more]

The world is interested in applying grid codes to increase the reliability of power systems through a micro-grid (MG). In a common practice, the MG comprises a wind farm, and/or photovoltaic (PV) arrays that are integrated with diesel generators and energy storage devices. Fault ride-through (FRT) capability is an important requirement of grid codes. FRT means that the MG is still connected to the grid during numerous disturbances such as faults. This is required to ensure that there is no loss of power generated due to grid faults. Reactive currents must be injected into the grid to increase the power system stability and restore voltage. To enhance FRT for doubly fed induction generator (DFIG) based WT installation, internal control modifications of rotor-side converters and grid-side converters are applied. The solutions that depend on these modifications are traditional and advanced control techniques. Advanced control techniques are needed due to the non-linear nature and less rob... [more]

This work presents a model for determining the availability of continuous systems at open pits by applying fuzzy logic and fuzzy inference systems. The applied model was formed by the synthesis of independent partial indicators of availability. The model is based on an expert system for assessing the availability of continuous mining systems. The availability of the system, as a complex state parameter, is decomposed into the partial indicators, reliability, and convenience of maintenance, and the fuzzy compositions, used for integration the partial indicators, are the max−min and min−max compositions. The advantage of this model in comparison to the conventional models is that it takes into account the effect of practical indicators of availability, does not require long-term monitoring, and records necessary to determine the time picture of the system state. This model for determining the availability has a role to help responsible persons at open pits in the planning and control of... [more]

Data-driven Automated Fault Detection and Diagnosis (AFDD) are recognized as one of the most promising options to improve the efficiency of Air-Handling Units (AHUs). In this study, the field operation of a typical single-duct dual-fan constant air volume AHU is investigated through a series of experiments carried out under Mediterranean (southern Italy) climatic conditions considering both fault-free and faulty scenarios. The AHU performances are analyzed while artificially introducing the following five different typical faults: (1) post-heating coil valve stuck at 100% (always open); (2) post-heating coil valve stuck at 0% (always closed); (3) cooling coil valve stuck at 100% (always open); (4) cooling coil valve stuck at 0% (always closed); (5) humidifier valve stuck at 0% (always closed). The measured faulty data are compared against the corresponding fault-free performance measured under the same boundary conditions with the aim of assessing the faults’ impact on both thermal/hyg... [more]

Ti-extraction blast furnace slag (EBFS) is a secondary slag produced by titanium extraction of titanium-bearing blast furnace slag (TBBFS), which is challenging to be used directly because of its residual carbon and chlorine. This study was performed to recover the residual carbon and remove chlorine from EBFS by froth flotation. The finely ground EBFS (FEBFS) contained graphitized carbon and khamrabaevite and had a 10.19% loss on ignition (LOI) and 5.52% Cl. The graphitized carbon was mainly recovered by flotation rather than khamrabaevite. Graphitized carbon appeared as flakes embedded in or stacked on the surface of the concentrate grains. The irregular-shaped particles were amorphous aluminosilicate glasses, whose presence adversely affected the quality and performance of the flotation concentrate. The Cl contents of the flotation concentrate and tailings obtained under the optimized flotation conditions were significantly reduced to 1.17% and 0.4%, respectively. The dechlorination... [more]

Open innovations (OI) are playing an increasingly important role in the innovative development (RI) of SMEs. This has led to a need to analyze the impact of OI on innovative development serving the implementation of the assumptions of sustainable development, the positive effect of which is to reduce the negative impact on the environment thanks to a more rational use of both natural and produced resources (e.g., energy). This development is described in this article as “sustainable innovative development”. Research was conducted on a sample of 800 SMEs in Poland using the quantitative method (questionnaire). The aim of this study was to identify the impact of OI on sustainable innovation development. This goal was achieved through the verification of three research hypotheses. It turns out that SMEs obtain significant benefits by exploring the environment, i.e., by showing a high level of willingness to cooperate with various entities in the environment for sustainable innovative deve... [more]

In China, environmental pollution responsibilities are divided according to administrative regions. However, because of the strong externality of environmental pollution, the movement of environmental pollution undoubtedly increases the complexity of pollution governance. To divide the responsibility of environmental pollution governance in each province, we effectively quantify the unequal relationship between environmental pollution costs and economic benefits in each province to understand the mechanism and characteristics of inter-provincial environmental pollution movement. Based on the regional input−output model and an inventory we compiled of sulfur dioxide(SO2) emissions of air pollutants in 2012, we calculate the implied inter-provincial environmental pollution emissions and economic benefits from trade, based on production and consumption (supply-side and demand-side). In addition, the movement relationship is explored, and the cost and economic value-added indexes of air po... [more]

This paper investigates the dynamics of an electromagnetic vortex bladeless wind turbine (VBWT) with a tunable mechanism. The tunable mechanism comprises a progressive-rate spring that is attached to an oscillating magnet inside an electromagnetic coil. The spring stiffness is progressively adjusted as the wind speed changes to tune the turbine fundamental frequency to match the shedding frequency of the vortex-induced vibration (VIV) due to the wind flow crossing over the oscillating mast. Coupled nonlinear equations of motion of the tunable turbine are developed using the lumped-mass representation and Lagrange formulation. Numerical results show that the tunable turbine performs effectively beyond a threshold wind speed. An analytical expression of the threshold speed is derived based on the mechanical fundamental frequency of the turbine. The analytical results are in reasonable agreement with the numerical evaluations. At a given wind speed past the threshold, the tunable turbine... [more]

Automation can now be found in nearly every industry. However, home automation has yet to reach Pakistan. This paper presents an Internet of Things smart kitchen project that includes automation and monitoring. In this project, a system was developed that automatically detects the kitchen temperature. It also monitors the humidity level in the kitchen. This system includes built-in gas detection sensors that detect any gas leaks in the kitchen and notify the user if the gas pressure in the kitchen exceeds a certain level. This system also allows the user to remotely control appliances such as freezers, ovens, and air conditioners using a mobile phone. The user can control gas levels using their phone with this system. In this paper, the ESP32, DHT11 Sensor, 5 V Relay X 8, and MQ-135 gas sensors create a smart kitchen by controlling the temperature, managing humidity, and detecting gas leakage. The system was built on an Arduino board that is connected to the Internet. The hardware was... [more]

In this work, hydrolysis lignin with nickel compounds deposited on the surface was prepared. The resulting material was introduced into the process of carbon dioxide assisted conversion and the catalytic activity of the deposited nickel compounds in this reaction was evaluated. Use of the obtained catalytic system increases CO2 conversion by more than 30% in the temperature range 450−800 °C. After the conversion process, the material was subjected to a study using a variety of physico-chemical analysis methods (TEM, SEM-EDX, and X-ray phase analysis). Physico-chemical methods of analysis of a sample calcined at 300 °C to decompose nickel nitrate revealed NiO nanoparticles with an average particle size of 16.9 nm.

Sprinkler skipping is an important issue in fire spread. In general, two sprinklers are installed in air conditioner rooms at the ceiling and 30 cm below to avoid spray failure by energy recovery ventilator in the ceiling. However, there is a problem in that sprinkler skipping occurs in the air conditioner room. In this study, the sprinkler skipping phenomenon was analyzed through numerical analysis and the applicability of the open type of sprinkler operation method was reviewed. As a result, when the upper sprinkler works, sprinkler skipping occurred in all cases. The lower sprinkler shall not rise above the operating temperature of 68.3 °C with a maximum temperature of 65 °C. In particular, the spray failure caused by the energy recovery ventilator reduces the sprinkler head temperature by more than 8 °C by concentrating the spray droplets. As an open type, simultaneous operation of two sprinklers is capable of obtaining an appropriate fire extinguishing effect by covering the fire... [more]

The research presented in this paper explains how the complex-vector-filter (CVF) method can help in minimizing the current harmonic of a grid-tied photovoltaic system. In fact, the harmonic-free positive sequence (HFPS) load current is used to produce referential sinusoidal currents. This control stabilizes the grid’s currents under unbalanced load currents, as well as mitigates undesirable harmonic load currents, while feeding clean active power to the grid. Thanks to the proposed controller, the performance, such as robustness, as well as the stability and dynamics of the CVF are more effective compared to the proportional-integral (PI) with phase-locked-loop (PLL) controller. Moreover, the CVF ensures robustness and stability during the synchronization between the photovoltaic (PV) generator and the utility grid system. The PI&PLL control presents higher active and reactive power fluctuations during synchronization. On the other hand, the CVF ensures the elimination of the reactive... [more]

Conveying systems play an essential role in the continuous horizontal transportation of raw materials in mining sites. Regular inspections of conveyor system structures and their components, especially idlers, are essential for proper maintenance. Traditional inspection methods are labor-intensive and hazardous; therefore, robot-based thermography can be considered a quality assessment tool for the precise detection and localization of overheated idlers in opencast mining sites. This paper proposes an infrared image processing pipeline for the automatic detection and analysis of overheated idlers. The proposed image processing pipeline can be used for the identification of significant temperature anomalies such as hotspots and hot areas in infrared images. For the identification of such defects in idlers, firstly, the histogram of captured infrared images was analyzed and improved through the pre-processing stages. Afterward, the location of thermal anomalies in infrared images was ext... [more]

The surface deposition of aviation fuel is a crucial and challenging issue in the application of air-to-fuel heat exchangers in aero-engines. The present study investigated the effect of pressure on the surface deposition of aviation fuel in a horizontal tube. Surface deposition distributions of aviation fuel RP-3 under different pressures (from 1.5 to 5.5 MPa) and different heat fluxes (from 0.08 to 0.4 MW/m2) were measured. Some experimental cases were numerically simulated to analyze the intrinsic mechanism of pressure affecting deposit formation. It was shown that pressure affects oxidative and pyrolytic deposition differently. Elevated pressure promotes the formation of pyrolytic deposits, whereas the oxidative deposition rate increases as pressure decreases. Pressure affects surface deposit formation via the physical properties of aviation fuel, especially density. The phase transition of fuel from liquid to vapor greatly accelerates the precipitation and deposition of insoluble... [more]

Characterization of stress-dependent single-phase and multiphase fluid transport in fractured geo-materials is essential for a wide range of applications, including CO2 sequestration, energy storage, and geo-energy extraction. However, pivotal studies on capillarity and multiphase fluid flow in deformable rock fractures are surprisingly sparse. In this study, we initially investigated the hydro-mechanical properties of an intact mixed-wet Calumet carbonate from the Waterways formation (Alberta) under isothermal conditions (40 °C). Then, we conducted core-flooding experiments using water and N2 to assess changes in the aperture, absolute permeability, relative permeability, and capillary pressure of an artificially fractured Calumet core in response to changes in effective confining stress during loading (0−10 MPa) and unloading (10−3 MPa). We quantified the fracture’s non-linear closure and hysteresis effect during the cyclic loading−unloading processes. We found that porosity and abso... [more]

Capacitance−resistance models (CRMs) are semi-analytical methods to estimate the production rate of either an individual producer or a group of producers based on historical observed production and injection rates using material balance and signal correlations between injectors and producers. Waterflood performance methods are applied to evaluate the waterflooding performance effect and to forecast the development index on the basis of Buckley−Leverett displacement theory and oil−water permeability curve. In this case study, we propose an approach that combines a capacitance−resistance model (CRM) modified by increasing the influence radius on the constraints and a waterflood performance equation between oil cut and oil accumulative production to improve liquid and oil production prediction ability. By applying the method, we can understand the waterflood performance, inter-well connectivities between injectors and producer, and production rate fluctuation better, in order to re-just t... [more]

The aim of current study is to investigate the significance of green and blue economic activities to mitigate the carbon emission in Saudi Arabia. We use the time series data which covers the period from 1990 to 2019. For empirical estimations, we use nonlinear ARDL approach which confirms that energy indicators and blue economic indicators are not mature enough to achieve carbon neutrality objectives. However, after Vision 2030 empirics, positive shocks in green indicators are turning down the carbon level. The findings of energy and blue indicators are useful for policy recommendations which help to achieve the sustainable environmental goals of Vision 2030.

The influence of high-rank coal’s pore characteristics on the physical properties, gas-bearing properties, and exploitation of coal reservoirs is becoming more and more prominent. How to establish the classification to describe the pore networks combining quantitative and qualitative characteristics has emerged as a major problem, which may offer a scientific foundation to deepen the understanding of this issue. In this research, the structure and fractal characteristics of reservoir pores were determined after analyzing 20 high-rank coal samples from Xinjing Coal Mine in the Qinshui Basin with the application of the high-pressure mercury intrusion method (HPMI) and argon ion polishing−field emission scanning electron microscopy (AIP−FESEM). The results show that the tested coal samples were bipolar distributed, with transitional pores and micropores dominating the pore volume, followed by macropores. The Menger sponge fractal models manifested two or three distinct straight-line segme... [more]

In this work, a novel ejector design concept of a swirl-bypass nozzle is proposed to improve off-design performance of CO2 two-phase ejectors. The swirl-bypass nozzle allows part of the flow to bypass into the ejector mixing chamber to generate swirl. The design of such a device is investigated using a 3D multiphase CFD model. An extensive experimental test campaign is conducted to validate the baseline homogeneous equilibrium CFD model. The model’s prediction motive mass flow rate within 2−12% error and suction mass flow rate was predicted with 3−50% error. Based on the tested ejector geometry, simulations of different ejector swirl-bypass inlets are conducted. The results show that, for the current design, total entrainment of the ejector is reduced by 2−20% with the swirl-bypass inlet. The axial position of the bypass inlet plays a primary role in the bypass inlet flow rate, and, consequently, in suction flow reduction. This is found to be due to the bypass flow blocking off the suc... [more]

In this paper, the effects of simultaneous air and water cooling on the energy performances of a single-pass hybrid PV/T system are experimentally investigated. Both air and water are used as coolants and are tested at four different mass flow rates, ranging from 0.0014 to 0.0026 kg/s. It is found that the overall efficiency of the PV/T system is dependent on the solar intensity and mass flow rate of coolants. Maximum PV/T system efficiency is found to be 62.2% for a simultaneous flow of water and air at a 0.0026 kg/s flow rate, which is 35.5% higher than the efficiency found at 0.0014 kg/s coolant flow rate. Maximum thermal energy outputs are 85.8 and 211.84 W/m2 while using air- and water-based coolants, respectively. Exergy analysis of the developed system indicates that exergy efficiency increased by up to two times by introducing simultaneous air and water cooling in this PV/T system.

Fuel cells are one of the zero-emission elements of modern automotive drive systems. This article presents theoretical identification of the component parameters of indicators for the fuel cell operating conditions. Activation, ohmic, and mass transport losses were identified. Current−voltage characteristics were provided along with an analysis of typical cell losses. The actual performance characteristics of fuel cells were analyzed for Toyota Mirai I and II generation vehicles. The fuel cells operating conditions were derived and analyzed in the context of real driving conditions. Therefore, urban, rural, and motorway conditions were used. The vehicles were equipped with PEM fuel cells supplying power equal to 114 kW (1st gen.) or 128 kW (2nd gen.). The average fuel cell stack power values depend on the driving conditions: urban (about 10 kW), rural (20 kW) and motorway (about 30−40 kW) driving modes. The different power ratings of fuel cells combined with different battery generatio... [more]

In power energy distribution networks, switchgear is considered critical equipment. This is because the act of monitoring the operation and condition of switchgear, as well as performing the required corrective maintenance on any potentially problematic equipment, is critical. A single event may harm thousands of customers over time and pose a significant risk to operational staff. Many considerations must be put in place before using outages to switch down the system since they may raise maintenance costs and disrupt the power supply to users. As a result, proper interpretation of switchgear status evaluations is critical for the early identification of possible faults. Existing ultrasound condition-based monitoring (CBM) diagnostic testing techniques require the tester to manually interpret test data. This study aims to review the status of the recent development of CBM techniques with faults in switchgear. The current trend in electrification will be toward the safety and sustainabi... [more]