Some studies have confirmed the neuroprotective effect of remote ischemic conditioning against stroke. Although numerous animal researches have shown that the neuroprotective effect of remote ischemic conditioning may...Some studies have confirmed the neuroprotective effect of remote ischemic conditioning against stroke. Although numerous animal researches have shown that the neuroprotective effect of remote ischemic conditioning may be related to neuroinflammation, cellular immunity, apoptosis, and autophagy, the exact underlying molecular mechanisms are unclear. This review summarizes the current status of different types of remote ischemic conditioning methods in animal and clinical studies and analyzes their commonalities and differences in neuroprotective mechanisms and signaling pathways. Remote ischemic conditioning has emerged as a potential therapeutic approach for improving stroke-induced brain injury owing to its simplicity, non-invasiveness, safety, and patient tolerability. Different forms of remote ischemic conditioning exhibit distinct intervention patterns, timing, and application range. Mechanistically, remote ischemic conditioning can exert neuroprotective effects by activating the Notch1/phosphatidylinositol 3-kinase/Akt signaling pathway, improving cerebral perfusion, suppressing neuroinflammation, inhibiting cell apoptosis, activating autophagy, and promoting neural regeneration. While remote ischemic conditioning has shown potential in improving stroke outcomes, its full clinical translation has not yet been achieved.展开更多
Each family has its own specifications and different volume of cultural capital which more or less stimulates the child development. Very specific is the case of book ownership in the family. The paper analyzes materi...Each family has its own specifications and different volume of cultural capital which more or less stimulates the child development. Very specific is the case of book ownership in the family. The paper analyzes material and cultural environment of present-day families in the north-western part of Slovak republic. The author presents the results of observation of some material conditions in Slovak families with primary school children and finds out their impact on the children＇s school success.展开更多
The results of the 2022-2025 study conducted for the vulnerability assessment of pastures and for the development of improvement measures on the degraded land sections in the arid and semi-arid provinces of the Caucas...The results of the 2022-2025 study conducted for the vulnerability assessment of pastures and for the development of improvement measures on the degraded land sections in the arid and semi-arid provinces of the Caucasus under the global climate change conditions are introduced in the current article.The main goal of our scientific work is to study and assess the current ecological and resource state of natural phytocenoses,pastures and hayfields in the arid and semi-arid landscapes under climate change.The paper presents the results of determining the areas and levels of degradation of the natural biogeocenoses and biogeocenoses of the pastures and hayfields in the mountain and highland landscapes.The results were obtained using remote sensing,field and laboratory studies and analyses.The conducted studies have revealed that along 34,174.5 ha pasture and 1342.0 meadows areas of the pastures at the Areni,Yeghegis,Yeghegnadzor and Vayq consolidated administrative territories situated in the arid and semi-arid zones of the Vayots Dzor Region high degradation was recorded in about 6508 hectares of pasture and 407 hectares of meadows areas,which is related to irregular and uncontrolled economic mismanagement of the local population and global climate change.To improve the ecological condition,accessibility and quality of ecosystem services of the pastures,hayfields and natural meadows,comprehensive restoration bioecological and agrotechnical measures have been proposed.They are aimed at improving the air,water and nutrient regimes of soils,at their bioprotection,as well as at the general increase in area and at improving the economic characteristics of the vegetation cover.Such measures on the ecosystem basis are appropriate in the context of enriching the qualitative composition of plants with useful ecological and economic bioecological characteristics,taking into account the characteristics of landscapes,weather and climatic conditions,and agricultural opportunities.展开更多
Japan’s aging rate (ratio of elderly aged 65 and older to total population) has exceeded 20%. The aim of this study was to clarify the relationships between Health Related Quality of Life, Body Mass Index (BMI), and ...Japan’s aging rate (ratio of elderly aged 65 and older to total population) has exceeded 20%. The aim of this study was to clarify the relationships between Health Related Quality of Life, Body Mass Index (BMI), and sleep quality. Subjects were 51 adults over 55 years old with chronic disease who living in the community. Instruments and structured interviews were used giving due consideration to privacy. Interviews were conducted within 10 - 20 minutes at the out-patient department. The evaluation instruments included bodymass index, Pittsburgh Sleep Quality Index (PSQI), Health Related Quality of Life (HRQOL), and Oral Health Impact Profile (OHIP-14). A significant positive correlation (ρ = 0.321, p < 0.05) between PSQI and QOL (OHIP-14) scores was confirmed with sleep quality being lower with lower QOL scores. A negative correlation (ρ = ?0.339, p < 0.05) between physical health component summary scores (PCS) and mental health component summary scores (MCS) of HRQOL was confirmed, demonstrating that PCS was low, and the level of MCS was high. Sleep quality was found lower among those with lower oral health-related QOL scores. Moreover, in subjects with lower MCS scores, the PCS scores were found to be higher. Accordingly, it was considered appropriate that dental treatment and care, support the maintenance of activities and sleep, and mental health promotion which are likely requisites critical for elderly persons’ maintenance of independent lifestyles in their familiar community.展开更多
Let the coordinate system xi of flat space-time to absorb a second rank tensor field Φij of the flat space-time deforming into a Riemannian space-time, namely, the tensor field Φuv is regarded as a metric tensor wit...Let the coordinate system xi of flat space-time to absorb a second rank tensor field Φij of the flat space-time deforming into a Riemannian space-time, namely, the tensor field Φuv is regarded as a metric tensor with respect to the coordinate system xu. After done this, xu is not the coordinate system of flat space-time anymore, but is the coordinate system of the new Riemannian space-time. The inverse operation also can be done. According to these notions, the concepts of the absorption operation and the desorption operation are proposed. These notions are actually compatible with Einstein’s equivalence principle. By using these concepts, the relationships of the Riemannian space-time, the de Donder conditions and the gravitational field in flat space-time are analyzed and elaborated. The essential significance of the de Donder conditions (the harmonic conditions or gauge) is to desorb the tensor field of gravitation from the Riemannian space-time to the Minkowski space-time with the Cartesian coordinates. Einstein equations with de Donder conditions can be solved in flat space-time. Base on Fock’s works, the equations of gravitational field in flat space-time are obtained, and the tensor expression of the energy-momentum of gravitational field is found. They all satisfy the global Lorentz covariance.展开更多
The search for the generating compatibility conditions (CC) of a given operator is a very recent problem met in general relativity in order to study the Killing operator for various standard useful metrics. Accordingl...The search for the generating compatibility conditions (CC) of a given operator is a very recent problem met in general relativity in order to study the Killing operator for various standard useful metrics. Accordingly, this paper can be considered as a natural continuation of a previous paper recently published in JMP under the title Minkowski, Schwarschild and Kerr metrics revisited. In particular, we prove that the intrinsic link existing between the lack of formal exactness of an operator sequence on the jet level, the lack of formal exactness of its corresponding symbol sequence and the lack of formal integrability (FI) of the initial operator is of a purely homological nature as it is based on the long exact connecting sequence provided by the so-called snake lemma in homological algebra. It is therefore quite difficult to grasp it in general and even more difficult to use it on explicit examples. It does not seem that any one of the results presented in this paper is known as most of the other authors who studied the above problem of computing the total number of generating CC are confusing this number with the degree of generality introduced by A. Einstein in his 1930 letters to E. Cartan. One of the motivating examples that we provide is so striking that it is even difficult to imagine that such an example could exist. We hope this paper could be used as a source of testing examples for future applications of computer algebra in general relativity and, more generally, in mathematical physics.展开更多
Natural language processing has got great progress recently. Controlling robots with spoken natural language has become expectable. With the reliability problem of this kind of control in mind a confirmation process o...Natural language processing has got great progress recently. Controlling robots with spoken natural language has become expectable. With the reliability problem of this kind of control in mind a confirmation process of natural language instruction should be included before carried out by the robot autonomously and the prototype dialog system was designed thus the standardization problem was raised for the natural and understandable language interaction. In the application background of remotely navigating a mobile robot inside a building with Chinese natural spoken language considering that as an important navigation element in instructions a place name can be expressed with different lexical terms in spoken language this paper proposes a model for substituting different alternatives of a place name with a standard one (called standardization). First a CRF (Conditional Random Fields) model is trained to label the term required be standardized then a trained word embedding model is to represent lexical terms as digital vectors. In the vector space similarity of lexical terms is defined and used to find out the most similar one to the term picked out to be standardized. Experiments show that the method proposed works well and the dialog system responses to confirm the instructions are natural and understandable.展开更多
Focusing on the Yangtze River economic zone,the previous geological researches are systematically summarized,resources and environment conditions and major geological problems which are needing to be concerned in land...Focusing on the Yangtze River economic zone,the previous geological researches are systematically summarized,resources and environment conditions and major geological problems which are needing to be concerned in land planning and construction are studied.The results show that the resource conditions of cultivated land,shale gas,geotherm,lithium and so on are superior in the Yangtze River economic zone,and the resources and environment conditions are conducive to develop the modern agriculture,clean energy industry and strategic emerging industries.3×1013 m^2 farmlands without heavy metal pollution are concentrated;there are three national level shale gas exploration and development bases with explored reserves of 5.441×1011 m^3;geothermal availability is 2.4×109 t of standard coal each year,equivalent to 19% of the amount of coal in 2014;Asia's largest energy lithium metal ore deposit is found.In some parts of Yangtze River economic zone,there are some major geological problems such as active faults,karst collapse,ground subsidence,landslide-collapse-debris flow,affecting the river-crossing channels,high-speed railway,urban agglomeration and green ecological corridor planning and construction.Those problems should be concerned,and the relevant suggestions and countermeasures are put forward.Meanwhile,the ideas to further support the development of the Yangtze River economic zone are put forward.展开更多
Increase in requirement of hydrosulphuric water for improvement of the population set the task of identification of places of their possible congestion for hydrogeological service. Earlier detection of such congestion...Increase in requirement of hydrosulphuric water for improvement of the population set the task of identification of places of their possible congestion for hydrogeological service. Earlier detection of such congestions was accidental at well-drilling of different function. Therefore, development of new methodical approaches of search and allocation of perspective zones of their formation was required. It was for this purpose necessary to study in what conditions and what factors have an impact on formation of underground hydrosulphuric water. So far, definition of communication attempts only with separate geochemical signs was known. Results of studying of influence on formations of hydrosulphuric water of such factors as lithologic and facial in combination with oil-and-gas content, the geological and structural and hydrodynamic mode are given in this work. It is established that the main sign for formation of hydrosulphuric water is existence of evaporite thickness and hydrocarbon congestions. Besides, it is shown that small depth (up to 2 km) of their bedding has to be an indispensable condition and existence of explosive violation on which there has to be a water infiltration (a geological and structural factor). In the Surkhandarya region, the hydrodynamic mode caused by inclined bedding of aquifers was also one of essential factors. Active water is an exchange process with washing away (oxidation) sulfate of the containing thicknesses and subsequently, its restoration in interaction with hydrocarbons with formation of hydrosulphuric water is described. The technique is developed and the expected card of perspective zones of formation of hydrosulphuric water is constructed.展开更多
The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time de...The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.展开更多
The alternating method based on the fundamental solutions of the infinite domain containing a crack,namely Muskhelishvili’s solutions,divides the complex structure with a crack into a simple model without crack which...The alternating method based on the fundamental solutions of the infinite domain containing a crack,namely Muskhelishvili’s solutions,divides the complex structure with a crack into a simple model without crack which can be solved by traditional numerical methods and an infinite domain with a crack which can be solved by Muskhelishvili’s solutions.However,this alternating method cannot be directly applied to the edge crack problems since partial crack surface of Muskhelishvili’s solutions is located outside the computational domain.In this paper,an improved alternating method,the spline fictitious boundary element alternating method(SFBEAM),based on infinite domain with the combination of spline fictitious boundary element method(SFBEM)and Muskhelishvili’s solutions is proposed to solve the edge crack problems.Since the SFBEM and Muskhelishvili’s solutions are obtained in the framework of infinite domain,no special treatment is needed for solving the problem of edge cracks.Different mixed boundary conditions edge crack problems with varies of computational parameters are given to certify the high precision,efficiency and applicability of the proposed method compared with other alternating methods and extend finite element method.展开更多
Novel exact solutions of one-dimensional transient dynamic piezoelectric problems for thickness polarized layers and disks, or length polarized rods, are obtained. The solutions are derived using a time-domain Green’...Novel exact solutions of one-dimensional transient dynamic piezoelectric problems for thickness polarized layers and disks, or length polarized rods, are obtained. The solutions are derived using a time-domain Green’s function method that leads to an exact analytical recursive procedure which is applicable for a wide variety of boundary conditions including nonlinear cases. A nonlinear damper boundary condition is considered in more detail. The corresponding nonlinear relationship between stresses and velocities at a current time moment is used in the recursive procedure. In addition to the exact recursive procedure that is effective for calculations, some new practically important explicit exact solutions are presented. Several examples of the time behavior of the output electric potential difference are given to illustrate the effectiveness of the proposed exact approach.展开更多
Tractor hydraulic fluids are tested to maximize their performance levels and to ensure manufacturer′s standards are met.Common tractor hydraulic fluid tests include: Gear Wear Protection,Brake Chatter Reduction,Wet-C...Tractor hydraulic fluids are tested to maximize their performance levels and to ensure manufacturer′s standards are met.Common tractor hydraulic fluid tests include: Gear Wear Protection,Brake Chatter Reduction,Wet-Clutch Capacity,and Pump Performance tests.These tests are run by Southwest Research Institute,in the U.S.A.,for tractors built by John Deere and Case-New Holland.This paper details current methods for evaluating tractor hydraulic fluids.The tests that are described utilize full size equipment and were developed by the tractor′s original equipment manufacturers(OEMs).展开更多
In this paper, we extend the reliable modification of the Adomian Decom-position Method coupled to the Lesnic’s approach to solve boundary value problems and initial boundary value problems with mixed boundary condit...In this paper, we extend the reliable modification of the Adomian Decom-position Method coupled to the Lesnic’s approach to solve boundary value problems and initial boundary value problems with mixed boundary conditions for linear and nonlinear partial differential equations. The method is applied to different forms of heat and wave equations as illustrative examples to exhibit the effectiveness of the method. The method provides the solution in a rapidly convergent series with components that can be computed iteratively. The numerical results for the illustrative examples obtained show remarkable agreement with the exact solutions. We also provide some graphical representations for clear-cut comparisons between the solutions using Maple software.展开更多
This study dealt with the rhythmic Qian 3410 of the intersalt shale series in the Qianjiang Depression,in which the geological condition for oil accumulation in the rhythmic shale was investigated by using the basic d...This study dealt with the rhythmic Qian 3410 of the intersalt shale series in the Qianjiang Depression,in which the geological condition for oil accumulation in the rhythmic shale was investigated by using the basic drilling,core and well logging data,as well as data obtained from the thin section identification,SEM,mercury injection,X-ray diffraction and rock freezing heat analyses.The study result indicated that:1)the intersalt shale series are characterized by TOC in a range of 0.35%-6.38%(averaging 3.19%),Types I and II1 organic matter,and from immature to mature oil,indicative of a potential for generating a great volume of immature oil;2)in the target layer,mineral compositions are complicated,which can divide into argillaceous dolomite facies,argillaceous limestone facies,dolomitic mudstone facies,and calcium-mirabilite-filling dolomitic mudstone facies;and 3)of them,the argillaceous dolomite facies is the most contributory,with reservoir spaces consisting of intergranular pores as dominant,as well as rare dissolution pores and seams.It is characterized by high organic abundance(4.23%-6.38%),high content of brittle mineral(50%-71%),low content of clay mineral(18%-33%),high porosity(10.8%-26.3%)and good oil-bearing properties(S1 distributed in 3.48-5.64 mg/g,and S1/TOC value in a range of 348-564 oil mg/g).Therefore,the argillaceous dolomite facies was considered the key target series to be explored for the intersalt shale oil in the study area in the coming days.展开更多
In addition to the organic matter type,abundance,thermal maturity,and shale reservoir space,the preservation conditions of source rocks play a key factor in affecting the quantity and quality of retained hydrocarbons ...In addition to the organic matter type,abundance,thermal maturity,and shale reservoir space,the preservation conditions of source rocks play a key factor in affecting the quantity and quality of retained hydrocarbons in source rocks of lacustrine shale,yet this aspect has received little attention.This paper,based on the case analysis,explores how preservation conditions influence the enrichment of mobile hydrocarbons in shale oil.Research showns that good preservation conditions play three key roles.(1)Ensure the retention of sufficient light hydrocarbons(C_(1)–C_(13)),medium hydrocarbons(C_(14)–C_(25))and small molecular aromatics(including 1–2 benzene rings)in the formation,which enhances the fluidity and flow of shale oil;(2)Maintain a high energy field(abnormally high pressure),thus facilitating the maximum outflow of shale oil;(3)Ensure that the retained hydrocarbons have the miscible flow condition of multi-component hydrocarbons(light hydrocarbons,medium hydrocarbons,heavy hydrocarbons,and heteroatomic compounds),so that the heavy hydrocarbons(C_(25+))and heavy components(non-hydrocarbons and asphaltenes)have improved fluidity and maximum flow capacity.In conclusion,in addition to the advantages of organic matter type,abundance,thermal maturity,and reservoir space,good preservation conditions of shale layers are essential for the formation of economically viable shale oil reservoirs,which should be incorporated into the evaluation criteria of shale oil-rich areas/segments and considered a necessary factor when selecting favorable exploration targets.展开更多
For critical engineering systems such as aircraft and aerospace vehicles, accurate Remaining Useful Life(RUL) prediction not only means cost saving, but more importantly, is of great significance in ensuring system re...For critical engineering systems such as aircraft and aerospace vehicles, accurate Remaining Useful Life(RUL) prediction not only means cost saving, but more importantly, is of great significance in ensuring system reliability and preventing disaster. RUL is affected not only by a system's intrinsic deterioration, but also by the operational conditions under which the system is operating. This paper proposes an RUL prediction approach to estimate the mean RUL of a continuously degrading system under dynamic operational conditions and subjected to condition monitoring at short equi-distant intervals. The dynamic nature of the operational conditions is described by a discrete-time Markov chain, and their influences on the degradation signal are quantified by degradation rates and signal jumps in the degradation model. The uniqueness of our proposed approach is formulating the RUL prediction problem in a semi-Markov decision process framework, by which the system mean RUL can be obtained through the solution to a limited number of equations. To extend the use of our proposed approach in real applications, different failure standards according to different operational conditions are also considered. The application and effectiveness of this approach are illustrated by a turbofan engine dataset and a comparison with existing results for the same dataset.展开更多
The paper develops the local convergence of Inexact Newton-Like Method(INLM)for approximating solutions of nonlinear equations in Banach space setting.We employ weak Lipschitz and center-weak Lipschitz conditions to p...The paper develops the local convergence of Inexact Newton-Like Method(INLM)for approximating solutions of nonlinear equations in Banach space setting.We employ weak Lipschitz and center-weak Lipschitz conditions to perform the error analysis.The obtained results compare favorably with earlier ones such as[7,13,14,18,19].A numerical example is also provided.展开更多
Dear Editor Research on neurodegenerative diseases is a hot topic worldwide[1],and MRI,genetics and epigenetics,and animal models have been commonly used.Considering species differences,research on human brain samples...Dear Editor Research on neurodegenerative diseases is a hot topic worldwide[1],and MRI,genetics and epigenetics,and animal models have been commonly used.Considering species differences,research on human brain samples is irreplaceable(2)Many countries and regions have built brain banks to collect and store brain tissue from donors.Samples provided by a brain bank can be used to study synaptic structure,protein,DNA,RNA[3,4],and lipids to illuminate the pathological mechanisms underlying neurodegenerative diseases.When brain tissue is used for gene expression research,the quantitative real-time polymerase chain reaction(RT-qPCR)is an accurate method,which simultaneously amplifies and quantifies the expression of target genes by measuring the intensity of fluorescence in each PCR cycle.展开更多
基金supported partly by the National Natural Science Foundation of China,No.82071332the Chongqing Natural Science Foundation Joint Fund for Innovation and Development,No.CSTB2023NSCQ-LZX0041 (both to ZG)。
文摘Some studies have confirmed the neuroprotective effect of remote ischemic conditioning against stroke. Although numerous animal researches have shown that the neuroprotective effect of remote ischemic conditioning may be related to neuroinflammation, cellular immunity, apoptosis, and autophagy, the exact underlying molecular mechanisms are unclear. This review summarizes the current status of different types of remote ischemic conditioning methods in animal and clinical studies and analyzes their commonalities and differences in neuroprotective mechanisms and signaling pathways. Remote ischemic conditioning has emerged as a potential therapeutic approach for improving stroke-induced brain injury owing to its simplicity, non-invasiveness, safety, and patient tolerability. Different forms of remote ischemic conditioning exhibit distinct intervention patterns, timing, and application range. Mechanistically, remote ischemic conditioning can exert neuroprotective effects by activating the Notch1/phosphatidylinositol 3-kinase/Akt signaling pathway, improving cerebral perfusion, suppressing neuroinflammation, inhibiting cell apoptosis, activating autophagy, and promoting neural regeneration. While remote ischemic conditioning has shown potential in improving stroke outcomes, its full clinical translation has not yet been achieved.
文摘Each family has its own specifications and different volume of cultural capital which more or less stimulates the child development. Very specific is the case of book ownership in the family. The paper analyzes material and cultural environment of present-day families in the north-western part of Slovak republic. The author presents the results of observation of some material conditions in Slovak families with primary school children and finds out their impact on the children＇s school success.
基金the framework of the Project 21T-4C045 of the Higher Education and Science Committee(RA)。
文摘The results of the 2022-2025 study conducted for the vulnerability assessment of pastures and for the development of improvement measures on the degraded land sections in the arid and semi-arid provinces of the Caucasus under the global climate change conditions are introduced in the current article.The main goal of our scientific work is to study and assess the current ecological and resource state of natural phytocenoses,pastures and hayfields in the arid and semi-arid landscapes under climate change.The paper presents the results of determining the areas and levels of degradation of the natural biogeocenoses and biogeocenoses of the pastures and hayfields in the mountain and highland landscapes.The results were obtained using remote sensing,field and laboratory studies and analyses.The conducted studies have revealed that along 34,174.5 ha pasture and 1342.0 meadows areas of the pastures at the Areni,Yeghegis,Yeghegnadzor and Vayq consolidated administrative territories situated in the arid and semi-arid zones of the Vayots Dzor Region high degradation was recorded in about 6508 hectares of pasture and 407 hectares of meadows areas,which is related to irregular and uncontrolled economic mismanagement of the local population and global climate change.To improve the ecological condition,accessibility and quality of ecosystem services of the pastures,hayfields and natural meadows,comprehensive restoration bioecological and agrotechnical measures have been proposed.They are aimed at improving the air,water and nutrient regimes of soils,at their bioprotection,as well as at the general increase in area and at improving the economic characteristics of the vegetation cover.Such measures on the ecosystem basis are appropriate in the context of enriching the qualitative composition of plants with useful ecological and economic bioecological characteristics,taking into account the characteristics of landscapes,weather and climatic conditions,and agricultural opportunities.
文摘Japan’s aging rate (ratio of elderly aged 65 and older to total population) has exceeded 20%. The aim of this study was to clarify the relationships between Health Related Quality of Life, Body Mass Index (BMI), and sleep quality. Subjects were 51 adults over 55 years old with chronic disease who living in the community. Instruments and structured interviews were used giving due consideration to privacy. Interviews were conducted within 10 - 20 minutes at the out-patient department. The evaluation instruments included bodymass index, Pittsburgh Sleep Quality Index (PSQI), Health Related Quality of Life (HRQOL), and Oral Health Impact Profile (OHIP-14). A significant positive correlation (ρ = 0.321, p < 0.05) between PSQI and QOL (OHIP-14) scores was confirmed with sleep quality being lower with lower QOL scores. A negative correlation (ρ = ?0.339, p < 0.05) between physical health component summary scores (PCS) and mental health component summary scores (MCS) of HRQOL was confirmed, demonstrating that PCS was low, and the level of MCS was high. Sleep quality was found lower among those with lower oral health-related QOL scores. Moreover, in subjects with lower MCS scores, the PCS scores were found to be higher. Accordingly, it was considered appropriate that dental treatment and care, support the maintenance of activities and sleep, and mental health promotion which are likely requisites critical for elderly persons’ maintenance of independent lifestyles in their familiar community.
文摘Let the coordinate system xi of flat space-time to absorb a second rank tensor field Φij of the flat space-time deforming into a Riemannian space-time, namely, the tensor field Φuv is regarded as a metric tensor with respect to the coordinate system xu. After done this, xu is not the coordinate system of flat space-time anymore, but is the coordinate system of the new Riemannian space-time. The inverse operation also can be done. According to these notions, the concepts of the absorption operation and the desorption operation are proposed. These notions are actually compatible with Einstein’s equivalence principle. By using these concepts, the relationships of the Riemannian space-time, the de Donder conditions and the gravitational field in flat space-time are analyzed and elaborated. The essential significance of the de Donder conditions (the harmonic conditions or gauge) is to desorb the tensor field of gravitation from the Riemannian space-time to the Minkowski space-time with the Cartesian coordinates. Einstein equations with de Donder conditions can be solved in flat space-time. Base on Fock’s works, the equations of gravitational field in flat space-time are obtained, and the tensor expression of the energy-momentum of gravitational field is found. They all satisfy the global Lorentz covariance.
文摘The search for the generating compatibility conditions (CC) of a given operator is a very recent problem met in general relativity in order to study the Killing operator for various standard useful metrics. Accordingly, this paper can be considered as a natural continuation of a previous paper recently published in JMP under the title Minkowski, Schwarschild and Kerr metrics revisited. In particular, we prove that the intrinsic link existing between the lack of formal exactness of an operator sequence on the jet level, the lack of formal exactness of its corresponding symbol sequence and the lack of formal integrability (FI) of the initial operator is of a purely homological nature as it is based on the long exact connecting sequence provided by the so-called snake lemma in homological algebra. It is therefore quite difficult to grasp it in general and even more difficult to use it on explicit examples. It does not seem that any one of the results presented in this paper is known as most of the other authors who studied the above problem of computing the total number of generating CC are confusing this number with the degree of generality introduced by A. Einstein in his 1930 letters to E. Cartan. One of the motivating examples that we provide is so striking that it is even difficult to imagine that such an example could exist. We hope this paper could be used as a source of testing examples for future applications of computer algebra in general relativity and, more generally, in mathematical physics.
基金Sponsored by the Basic Research Development Program of China ( Grant No. 2013CB03554)the Fundamental Research Funds for Universities, Central South University (Grant No. 2017zzts394).
文摘Natural language processing has got great progress recently. Controlling robots with spoken natural language has become expectable. With the reliability problem of this kind of control in mind a confirmation process of natural language instruction should be included before carried out by the robot autonomously and the prototype dialog system was designed thus the standardization problem was raised for the natural and understandable language interaction. In the application background of remotely navigating a mobile robot inside a building with Chinese natural spoken language considering that as an important navigation element in instructions a place name can be expressed with different lexical terms in spoken language this paper proposes a model for substituting different alternatives of a place name with a standard one (called standardization). First a CRF (Conditional Random Fields) model is trained to label the term required be standardized then a trained word embedding model is to represent lexical terms as digital vectors. In the vector space similarity of lexical terms is defined and used to find out the most similar one to the term picked out to be standardized. Experiments show that the method proposed works well and the dialog system responses to confirm the instructions are natural and understandable.
文摘Focusing on the Yangtze River economic zone,the previous geological researches are systematically summarized,resources and environment conditions and major geological problems which are needing to be concerned in land planning and construction are studied.The results show that the resource conditions of cultivated land,shale gas,geotherm,lithium and so on are superior in the Yangtze River economic zone,and the resources and environment conditions are conducive to develop the modern agriculture,clean energy industry and strategic emerging industries.3×1013 m^2 farmlands without heavy metal pollution are concentrated;there are three national level shale gas exploration and development bases with explored reserves of 5.441×1011 m^3;geothermal availability is 2.4×109 t of standard coal each year,equivalent to 19% of the amount of coal in 2014;Asia's largest energy lithium metal ore deposit is found.In some parts of Yangtze River economic zone,there are some major geological problems such as active faults,karst collapse,ground subsidence,landslide-collapse-debris flow,affecting the river-crossing channels,high-speed railway,urban agglomeration and green ecological corridor planning and construction.Those problems should be concerned,and the relevant suggestions and countermeasures are put forward.Meanwhile,the ideas to further support the development of the Yangtze River economic zone are put forward.
文摘Increase in requirement of hydrosulphuric water for improvement of the population set the task of identification of places of their possible congestion for hydrogeological service. Earlier detection of such congestions was accidental at well-drilling of different function. Therefore, development of new methodical approaches of search and allocation of perspective zones of their formation was required. It was for this purpose necessary to study in what conditions and what factors have an impact on formation of underground hydrosulphuric water. So far, definition of communication attempts only with separate geochemical signs was known. Results of studying of influence on formations of hydrosulphuric water of such factors as lithologic and facial in combination with oil-and-gas content, the geological and structural and hydrodynamic mode are given in this work. It is established that the main sign for formation of hydrosulphuric water is existence of evaporite thickness and hydrocarbon congestions. Besides, it is shown that small depth (up to 2 km) of their bedding has to be an indispensable condition and existence of explosive violation on which there has to be a water infiltration (a geological and structural factor). In the Surkhandarya region, the hydrodynamic mode caused by inclined bedding of aquifers was also one of essential factors. Active water is an exchange process with washing away (oxidation) sulfate of the containing thicknesses and subsequently, its restoration in interaction with hydrocarbons with formation of hydrosulphuric water is described. The technique is developed and the expected card of perspective zones of formation of hydrosulphuric water is constructed.
文摘The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.
基金supported by the National Natural Science Foundation of China(51078150)the National Natural Science Foundation of China(11602087)+1 种基金the State Key Laboratory of Subtropical Building Science,South China University of Technology(2017ZB32)National Undergraduate Innovative and Entrepreneurial Training Program(201810561180).
文摘The alternating method based on the fundamental solutions of the infinite domain containing a crack,namely Muskhelishvili’s solutions,divides the complex structure with a crack into a simple model without crack which can be solved by traditional numerical methods and an infinite domain with a crack which can be solved by Muskhelishvili’s solutions.However,this alternating method cannot be directly applied to the edge crack problems since partial crack surface of Muskhelishvili’s solutions is located outside the computational domain.In this paper,an improved alternating method,the spline fictitious boundary element alternating method(SFBEAM),based on infinite domain with the combination of spline fictitious boundary element method(SFBEM)and Muskhelishvili’s solutions is proposed to solve the edge crack problems.Since the SFBEM and Muskhelishvili’s solutions are obtained in the framework of infinite domain,no special treatment is needed for solving the problem of edge cracks.Different mixed boundary conditions edge crack problems with varies of computational parameters are given to certify the high precision,efficiency and applicability of the proposed method compared with other alternating methods and extend finite element method.
文摘Novel exact solutions of one-dimensional transient dynamic piezoelectric problems for thickness polarized layers and disks, or length polarized rods, are obtained. The solutions are derived using a time-domain Green’s function method that leads to an exact analytical recursive procedure which is applicable for a wide variety of boundary conditions including nonlinear cases. A nonlinear damper boundary condition is considered in more detail. The corresponding nonlinear relationship between stresses and velocities at a current time moment is used in the recursive procedure. In addition to the exact recursive procedure that is effective for calculations, some new practically important explicit exact solutions are presented. Several examples of the time behavior of the output electric potential difference are given to illustrate the effectiveness of the proposed exact approach.
文摘Tractor hydraulic fluids are tested to maximize their performance levels and to ensure manufacturer′s standards are met.Common tractor hydraulic fluid tests include: Gear Wear Protection,Brake Chatter Reduction,Wet-Clutch Capacity,and Pump Performance tests.These tests are run by Southwest Research Institute,in the U.S.A.,for tractors built by John Deere and Case-New Holland.This paper details current methods for evaluating tractor hydraulic fluids.The tests that are described utilize full size equipment and were developed by the tractor′s original equipment manufacturers(OEMs).
文摘In this paper, we extend the reliable modification of the Adomian Decom-position Method coupled to the Lesnic’s approach to solve boundary value problems and initial boundary value problems with mixed boundary conditions for linear and nonlinear partial differential equations. The method is applied to different forms of heat and wave equations as illustrative examples to exhibit the effectiveness of the method. The method provides the solution in a rapidly convergent series with components that can be computed iteratively. The numerical results for the illustrative examples obtained show remarkable agreement with the exact solutions. We also provide some graphical representations for clear-cut comparisons between the solutions using Maple software.
基金funded by the 2018 Undergraduate Training Program for Innovation and Entrepreneurship of Yangtze University,the project number is 2018267.
文摘This study dealt with the rhythmic Qian 3410 of the intersalt shale series in the Qianjiang Depression,in which the geological condition for oil accumulation in the rhythmic shale was investigated by using the basic drilling,core and well logging data,as well as data obtained from the thin section identification,SEM,mercury injection,X-ray diffraction and rock freezing heat analyses.The study result indicated that:1)the intersalt shale series are characterized by TOC in a range of 0.35%-6.38%(averaging 3.19%),Types I and II1 organic matter,and from immature to mature oil,indicative of a potential for generating a great volume of immature oil;2)in the target layer,mineral compositions are complicated,which can divide into argillaceous dolomite facies,argillaceous limestone facies,dolomitic mudstone facies,and calcium-mirabilite-filling dolomitic mudstone facies;and 3)of them,the argillaceous dolomite facies is the most contributory,with reservoir spaces consisting of intergranular pores as dominant,as well as rare dissolution pores and seams.It is characterized by high organic abundance(4.23%-6.38%),high content of brittle mineral(50%-71%),low content of clay mineral(18%-33%),high porosity(10.8%-26.3%)and good oil-bearing properties(S1 distributed in 3.48-5.64 mg/g,and S1/TOC value in a range of 348-564 oil mg/g).Therefore,the argillaceous dolomite facies was considered the key target series to be explored for the intersalt shale oil in the study area in the coming days.
基金Supported by the National Natural Science Foundation of China(U22B6004)Project of PetroChina Research Institute of Petroleum Exploration and Development(2022yjcq03)Core Technology Key Project of China Petroleum Changqing Oilfield Company(KJZX2023-01).
文摘In addition to the organic matter type,abundance,thermal maturity,and shale reservoir space,the preservation conditions of source rocks play a key factor in affecting the quantity and quality of retained hydrocarbons in source rocks of lacustrine shale,yet this aspect has received little attention.This paper,based on the case analysis,explores how preservation conditions influence the enrichment of mobile hydrocarbons in shale oil.Research showns that good preservation conditions play three key roles.(1)Ensure the retention of sufficient light hydrocarbons(C_(1)–C_(13)),medium hydrocarbons(C_(14)–C_(25))and small molecular aromatics(including 1–2 benzene rings)in the formation,which enhances the fluidity and flow of shale oil;(2)Maintain a high energy field(abnormally high pressure),thus facilitating the maximum outflow of shale oil;(3)Ensure that the retained hydrocarbons have the miscible flow condition of multi-component hydrocarbons(light hydrocarbons,medium hydrocarbons,heavy hydrocarbons,and heteroatomic compounds),so that the heavy hydrocarbons(C_(25+))and heavy components(non-hydrocarbons and asphaltenes)have improved fluidity and maximum flow capacity.In conclusion,in addition to the advantages of organic matter type,abundance,thermal maturity,and reservoir space,good preservation conditions of shale layers are essential for the formation of economically viable shale oil reservoirs,which should be incorporated into the evaluation criteria of shale oil-rich areas/segments and considered a necessary factor when selecting favorable exploration targets.
基金the National Natural science Foundation of China (No. 71701008) for supporting this research
文摘For critical engineering systems such as aircraft and aerospace vehicles, accurate Remaining Useful Life(RUL) prediction not only means cost saving, but more importantly, is of great significance in ensuring system reliability and preventing disaster. RUL is affected not only by a system's intrinsic deterioration, but also by the operational conditions under which the system is operating. This paper proposes an RUL prediction approach to estimate the mean RUL of a continuously degrading system under dynamic operational conditions and subjected to condition monitoring at short equi-distant intervals. The dynamic nature of the operational conditions is described by a discrete-time Markov chain, and their influences on the degradation signal are quantified by degradation rates and signal jumps in the degradation model. The uniqueness of our proposed approach is formulating the RUL prediction problem in a semi-Markov decision process framework, by which the system mean RUL can be obtained through the solution to a limited number of equations. To extend the use of our proposed approach in real applications, different failure standards according to different operational conditions are also considered. The application and effectiveness of this approach are illustrated by a turbofan engine dataset and a comparison with existing results for the same dataset.
文摘The paper develops the local convergence of Inexact Newton-Like Method(INLM)for approximating solutions of nonlinear equations in Banach space setting.We employ weak Lipschitz and center-weak Lipschitz conditions to perform the error analysis.The obtained results compare favorably with earlier ones such as[7,13,14,18,19].A numerical example is also provided.
基金supported by grants from the National Natural Science Foundation of China (81271239, 81771205, and 91632113)the Natural Science Foundation and Major Basic Research Program of Shanghai Municipality, China (16JC1420500 and 16JC1420502)+1 种基金the CAMS Innovation Fund for Medical Sciences (2017-I2M-3-008)sponsored by the China Human Brain Bank Consortium
文摘Dear Editor Research on neurodegenerative diseases is a hot topic worldwide[1],and MRI,genetics and epigenetics,and animal models have been commonly used.Considering species differences,research on human brain samples is irreplaceable(2)Many countries and regions have built brain banks to collect and store brain tissue from donors.Samples provided by a brain bank can be used to study synaptic structure,protein,DNA,RNA[3,4],and lipids to illuminate the pathological mechanisms underlying neurodegenerative diseases.When brain tissue is used for gene expression research,the quantitative real-time polymerase chain reaction(RT-qPCR)is an accurate method,which simultaneously amplifies and quantifies the expression of target genes by measuring the intensity of fluorescence in each PCR cycle.
