In this paper, different mathematical expressions are derived to compute the residual magnitude of voltage caused by faults along the line and on the bus. Symmetrical and unsymmetrical faults are taken into consideration, and the consequences of the various fault distributions are considered. A new way of assessing a sag is proposed that incorporates the method of fault position and mathematical expression based on sequence currents and voltages. The fault impedance is introduced to obtain a better result. A fast and efficient load flow analysis technique produces quick computational results. In addition, the sag analysis is performed using the bivariate joint discrete probability distribution method that gives a clear idea about the probability of occurrence of sag in a meshed network. The suggested approach is applied in the IEEE 39-bus system and with an existing real-time electrical power distribution system in India.

Energy density, which is an important indicator of the performance of solid propellants, is known to increase with the addition of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20). However, it remains unclear how CL-20 affects the decomposition of ammonium perchlorate (AP) and energy release. Here, the effects of CL-20 on the combustion performance and agglomeration of propellants were investigated. The addition of CL-20 decreased AP decomposition temperature and the energy required for the transformation of AP crystals from orthorhombic to cubic. The burning rate and pressure exponent of the propellant with 42% CL-20 were significantly higher than those of the propellant containing 20% CL-20. Thus, adding CL-20 to the propellant improves the energy characteristics and burning rate and the pressure exponent increases. At low combustion chamber pressure, the agglomeration of the propellant containing a high content of CL-20 will be blown away from the combustion surfac... [more]

Emissions from vehicles can be measured on the road or in laboratories using dynamometers that simulate the forces that a vehicle is subject to while driving on the road. In the light-duty vehicle regulations, only roller-type dynamometers are allowed. For hub-type dynamometers, due to the direct connection of the dynamometers to the wheel hubs, additional parameters that are used are rotational mass, dynamic wheel radius, and the tire force−slip relationship. Following up on an experimental study which showed that equivalent emission results can be achieved between roller- and hub-type dynamometers, this work presents and evaluates methods to determine parameters used by a hub-type dynamometer for mimicking roller-type dynamometer behavior. It also discusses methods to determine the parameters to simulate specific road conditions or when using only a hub-type dynamometer. The results show that using a constant dynamic radius for each wheel and a linear tire force−slip relationship is... [more]

The use of agroforestry residues for energy purposes has long been a reality in Brazil. About 84.8% of the produced electricity comes from renewable resources; vegetable biomass contributes 9.1% to this total. This percentage has the potential to increase if Amazon biomass residues are processed to be used as fuel. The major difficulty for this scenario is the lack of available information on energy properties, mainly the HHVs for Amazon agroforestry biomass types. Considering that there are important deviations in the equations for predicting the HHVs of Amazon biomass types in the literature, the main objective of this work was to propose equations to determine the HHVs of these biomass types using the proximate or ultimate analysis results as input. The methodology adopted to develop such equations was simple and multiple linear regression methods, using experimental results for HHVs and proximate and ultimate analyses for biomass types from the north region of Brazil. Four distinct... [more]

The urban power distribution system is one of the most complex artificial systems in the world [...]

Traditional high-voltage reactor monitoring and diagnosis research has problems such as high sampling demand, difficulty in noise reduction on site, many false alarms, and lack of on-site data. In order to solve the above problems, this paper proposes an acoustic−electric fusion high-voltage reactor acquisition system and defect diagnosis method based on reactor pulse current and ultrasonic detection signal. Using the envelope peak signal as the basic detection data, the sampling requirement of the system is reduced. To fill the missing data with partial discharge (PD) information, a method based on k-nearest neighbor (KNN) is proposed. An adaptive noise reduction method is carried out, and a noise threshold calculation method is given for the field sensors. A joint analysis method of acoustic and electrical signals based on correlation significance is established to determine whether a discharge event has occurred based on correlation significance. Finally, the method is applied to a... [more]

Crossfield is located in the province of Alberta in Canada and is one of the most well-known reservoirs of hydrocarbons. Since the 1950s, there has been continuous exploitation of more than 10 formations such as Cardium, Viking, Ellerslie, Elkton, Shunda, and Wabamun. Because of its location near the Foothills, the southwestern part of the Western Canada Sedimentary Basin, the Crossfield area has a complex geology and relatively deeper reservoirs, therefore requiring an in-depth examination of each formation. In this study, geological, technical, and economic analyses were performed on each formation within the 10 sections of the study lands in the Crossfield area. As the result of the study, there was potential for drilling 48 horizontal wells in the Cardium A zone and the Viking formation. In addition, it turned out to be economically feasible even at the WTI price of 60 dollars per barrel considering Alberta’s Royalty Framework, which is determined by the production rate and the pri... [more]

This paper presents the results of detonation parameters for ammonium nitrate-polyhydroxy alcohol mixtures and ternary explosive compositions modified by flaked aluminium. The detonation velocities, overpressures of blast waves and their specific impulses were determined. It was shown that the viscosity of liquid fuels is the leading property that determines the detonation parameters of the tested compositions.

In shear wave far detection logging, dipole-source radiation is the main factor influencing the amplitude of the reflected shear waves. In this paper, a method is derived with the far-field asymptotic solution to calculate the dipole-source radiation of shear waves in a fluid-filled borehole. Then the dipole-source radiation of the shear waves is simulated under both low and high frequencies. In addition, the influences of formation elastic parameters on the dipole-source radiation of the shear waves are analyzed and the variations of the radiation characteristics of the shear wave with source main frequency and borehole radius are compared. Results show that the density and compressional wave velocity of the formation have little effect on the dipole-source radiation of the shear waves. However, the shear wave velocity not only affects the shear wave amplitude radiated to the formation by the dipole source (radiation performance), but also affects the energy distribution of the shear... [more]

SAGD (Steam Assisted Gravity Drainage) is used in Canadian fields where there are interlayers that impede steam chamber development and thus impede production. Many experiments have been conducted on the effect of interlayers on oil recovery. However, the swelling characteristics of interlayers under different conditions, as well as the possible clay mineral transformation and particle migration of clay particles at high temperatures, are rarely studied. In this paper, the swelling characteristics of natural oil sands and artificial clay samples were studied by high temperature hydration swelling experiments to obtain a better comparison. The effects of temperature, pressure and solution type on the swelling rate of oil sand were studied. The uniaxial compressive strength of the core in the presence of clay was studied by the scribe test. In addition, before and after the aging test at 220 °C and 2.5 MPa, the clay mineral composition was studied by the X-ray diffraction method, and the... [more]

Affected by Tianshan uplift, the southern Junggar Basin has experienced multi-stage tectonic movements and formed many large-scale anticlines with zonal distribution. The key to hydrocarbon exploration is to accurately implement anticline traps. This paper is guided by the fault-related folds theory to tectonically interpret several seismic profiles in the southern Junggar Basin and then summarize the anticline types and their hydrocarbon accumulation characteristics. This paper showed that the southern Junggar Basin has a tectonic assemblage pattern of “multi-detachment layers and multi-phase superposition”. According to the superimposed shape of the anticlines, they could be divided into overthrust anticlines, compound anticlines and multiple superimposed anticlines, and the horizontal and vertical positions of the different types of anticlines are different. The hydrocarbon accumulating characteristics of the different types of anticlines are shown to be different. The highs of the... [more]

We have developed a carbon nanotube (CNT) pad to replace carbon black, which is essential for electric muscle stimulation (EMS) suits that can provide efficient exercise effects in a short time. The optimized CNT pad had 10 times lower concentration but showed 20 times lower resistance than the carbon black pad. In the case of the peak voltage indicating the EMS performance, it was confirmed that the CNT (4.0 wt%) was 25.9 V and the carbon black (40 wt%) was 6.5 V, which was about 4 times better. CNT added increased from 4.0 wt% to 10.0 wt%, and the peak voltage increased from 25.9 V to 26.8 V, but the output voltage was not significantly improved compared to the amount of CNT added. These experimental results are expected to show higher EMS properties than carbon black because carbon nanotubes and silicon are agglomerated to form a particle-like shape.

Great attention has been paid in recent months to high energy prices, including fuel prices. Numerous studies present the threat this poses to economic growth, but history already knows such situations. Therefore, the elementary question was posed: How do fuel prices affect trade and economic growth? The research was based on the Polish economy between 2000 and 2020. Poland is an importer of energy commodities, so it should exhibit strong sensitivity to fuel price changes. A VAR model was created for the Polish economy, including fuel prices, seaborne trade, gross domestic product, and inflation. The results demonstrate that the Polish economy is quite resilient to fuel market turbulence. Obviously enough, it is easier to function in the conditions of lower fuel prices, but high prices are not a reason to panic. Moreover, ongoing technological progress allows economies to weather fuel market crises more easily than was the case back in the 20th century. Therefore, one may unequivocally... [more]

CO2 hydrate formation and dissociation are the fundamental processes for investigating hydrate-based carbon storage. To better understand CO2 hydrate phase behaviors in the presence of surfactant and solid additives, this study reports the effects of Sodium Dodecyl Sulfate (SDS) and micron Cu particles on the formation of CO2 hydrates in the presence of porous quartz sands in a lab-scale reactor. This research is part of a wider study focused on defining the properties of solid additives, produced via gas-atomization, on the formation and dissociation of gas hydrates. The morphology of CO2 hydrate formed in SDS solution shows dispersed crystal particles due to the increase of surface tension. SDS works as the kinetic promoter on CO2 hydrates formation whereas the addition of Cu particles inhibits CO2 gas consumption. The mixture additives show a faint kinetic inhibit effect, in which the Brownian motion restrictions may be responsible for the inhibition of CO2 hydrate production. The s... [more]

This paper devises an output-feedback multi-loop positioning technique adopting the speed observer and multi-motor synchronizer, targeting the dual (master and slave) motor elevator system applications, providing the three contributions. First, the order-reduction observer continuously extracts the speed information from the motor position measurement, independent of the system model information. Second, the order-reduction stabilizer accomplishes the speed synchronization tasks for both the master and slave motors. Third, the resultant feedback system guarantees to exponentially recover the desired first-order transfer function from the reference to the actual motor position despite the model-plant mismatches. The prototype elevator system adopting the dual motor experimentally validates the practical advantages of the proposed technique.

In this paper, the theoretical properties of transients in three-phase networks, including the fourth wire and unbalanced source, are systematically investigated by resorting to several analytical tools. First, a Cartesian space vector is introduced to provide the geometrical three-dimensional representation of a three-phase voltage/current transient. It is shown that a voltage/current transient can be always represented as a three-dimensional trajectory leaving one plane (corresponding to the previous steady state) towards another plane (corresponding to the new steady state at the end of the transient). The quantity driving the trajectory from one plane to another is the Park/Clarke zero component. Second, the Clarke transformation is used to study the original three-phase circuit as a superposition of two independent transients: the transient of the Clarke space vectors and the transient of the Clarke zero components. Third, the Park transformation is used to evaluate the dq0 compon... [more]

As a new and unconventional reservoir, Quaternary mudstone biogas reservoirs in the Qaidam Basin are widely distributed and thick. They have great potential for biogas exploration. However, the mudstone biogas reservoirs in this area characterized by weak cementation, high clay content, and easy hydrolysis. Using existing methods, it is difficult to obtain the rock electrical parameters and evaluate the saturation. This greatly affects the evaluation of oil and gas reserves. This study selected core samples from the Quaternary mudstone biogas reservoir in Qaidam Basin, prepared the samples through core conformation pretreatment, and conducted rock electrical experiments using the self-absorption water augmentation method to obtain the rock electrical parameters of the mudstone biogas reservoirs for the first time. Then, the factors influencing the rock electrical parameters of the mudstone biogas reservoir were analyzed. The results showed that: (1) the porosity of the mudstone core sa... [more]

In this study, we propose the use of a short-distance and fixed-type wireless power transmission transformer via a half-bridge LLC resonant converter. A ceramic insulating layer was used instead of an air gap, meaning that the heat generated from the transformer core and the PCB winding was quickly transferred to the external metal case, with the ceramic insulating layer acting as a heat pipe. In order to stabilize the output voltage, we proposed the use of IR photo tunnel technology, and it was applied to two ceramic insulating layers so that the voltage error signal of the secondary output voltage could be transmitted as light to the primary side. As a result, it was possible to physically separate the primary and secondary sides of the power circuit centering on the ceramic insulating layer. The experiment was carried out with the input voltage of 400 V, the output voltage of 54 V, the maximum output power of 1 kW, and the switching frequency of 1.3 MHz or higher. As a result, the m... [more]

The increase in heterogeneous data in the building energy domain creates a difficult challenge for data integration. Schema matching, which maps the raw data from the building energy domain to a generic data model, is the necessary step in data integration and provides a unique representation. Only a small amount of labeled data for schema matching exists and it is time-consuming and labor-intensive to manually label data. This paper applies semantic-similarity methods to the automatic schema-mapping process by combining knowledge from natural language processing, which reduces the manual effort in heterogeneous data integration. The active-learning method is applied to solve the lack-of-labeled-data problem in schema matching. The results of the schema matching with building-energy-domain data show the pre-trained language model provides a massive improvement in the accuracy of schema matching and the active-learning method greatly reduces the amount of labeled data required.

The IT infrastructure is the basis for the efficient and effective flow of logistic information between the individual elements of the logistical system. Therefore, the aim of this research was to assess the diversification of equipment in IT infrastructure in enterprises in Central Pomerania in Poland. The research was conducted in 2021 using the CAWI method. The research covers five categories of IT infrastructure: IT equipment, software/applications, means of communication, devices cooperating in the smart internet network and other devices. The study was conducted on a sample of 353 enterprises located in the area of Central Pomerania. The results of the conducted research indicate that the degree of use of the IT infrastructure in the analyzed enterprises varies. Taking into account the size of the enterprise, IT infrastructure is much more often used by large and medium enterprises than by small and micro enterprises. In addition, the results also show the diversification of the... [more]

The issue of shifting loads from road to rail is always vivid when it comes to reducing CO2 emissions from transport. Practically not every load transported by road vehicles over a long distance can be transferred to rail. Additionally, the potential of the railway lines is limited, which means that the network is not able to accept huge amounts of loads from road transport. In the article, attention was paid to the typology of cargo susceptible to changing the means of transport. The article discusses the factors influencing the real possibility of CO2 reduction by changing the mode of transport. The analysis and calculation example of the selected region in Poland is presented.

This paper presents the results of detonation and explosion characteristics for ammonium nitrate, aluminium, and aluminium-magnesium alloy powder mixtures. The following parameters were determined: detonation velocities, blast waves overpressure and their specific impulses. The emission of radiation was recorded, and the history of temperature of the detonation products cloud was established. It was shown that addition of aluminium-magnesium alloy powder increases blast waves’ characteristics. Moreover, it increases the time of the afterburning reaction after detonation and increases the temperature of detonation products.

In the high-speed rail industry, the overhead contact line erected along the railroad is used to supply the electricity to the high-speed train via a pantograph on the carbody’s roof. This work attempts to explore the effect of contact line pre-sag on the contact quality between the pantograph and the contact line. A nonlinear finite element approach is implemented to build the overhead contact line system with accurate description of the pre-sag of the contact line. Through a nonlinear solution, the effect of contact line pre-sag on the contact force is analysed with different train speeds and tension classes. The analysis result indicates the feasibility of tuning the pre-sag to improve the interaction performance at a given speed and tension class. In the low-speed range, the change of pre-sag does not have a significant effect on the interaction performance. However, when the speed increases up to a certain value, the effect of pre-sag on the contact force is nonnegligible. The inc... [more]

We report a quantitative study of the effect of low-concentration methanol (MeOH) on the formation and dissociation of hydrates based on CH4 and CO2/N2 guest molecules. The kinetic promotion and dissociation ability of MeOH is also compared with the anionic surfactant sodium dodecyl sulfate (SDS, 100 ppm, 50 ppm). The effects of concentration changes (1 wt% and 5 wt%), pressure (p = 80−120 bar), guest molecules (CH4 and CO2), and temperature (1 °C and below 0 °C) are investigated using slow constant ramp (SCR) and isothermal (IT) temperature schemes. The results show that the kinetics are affected by the guest molecule and MeOH concentration. For CH4 gas, 5 wt% MeOH shows better promotion, while for CO2/N2 gas mixtures, 1 wt% MeOH gives better promotion. This conclusion agrees well with our previous results demonstrating optimal CH4 recovery and CO2 storage in the presence of 5 wt% MeOH. The promoting and inhibiting properties of MeOH could be beneficial in CH4 production from gas hydr... [more]

From a global perspective, carbon emissions are a global problem that needs to be solved urgently. At present, 61% of countries have committed to achieving net zero emissions. Compared with industry and construction, the transportation sector has become the focus and challenge for countries to achieve carbon neutrality due to the characteristics of strong mobility, scattered emission sources, and complex social behaviors. Therefore, the issue of carbon emissions in the transportation industry has become the focus of academic attention. This paper first calculates the carbon emission efficiency (CEE) of the regional transportation industry through the super-efficiency SBM model and then evaluates its regional differentiation characteristics through the Theil index, which has important practical significance for reducing regional carbon emissions. The results show that the national transportation CEE average value is 0.612, a relatively low level. The spatial distribution of China’s tran... [more]