3-D converted-wave data were acquired using digital MEMS （micro-electromechanical system） three component （3C） sensors in the alternating sand and shale sequence in the overburden of the Shengli Ken-71 area. This ...3-D converted-wave data were acquired using digital MEMS （micro-electromechanical system） three component （3C） sensors in the alternating sand and shale sequence in the overburden of the Shengli Ken-71 area. This gives rise to serious non-hyperbolic moveout effects in the converted-wave data due to both the asymmetrical ray path and anisotropic effects. Conventional velocity analysis and moveout correction based on isotropic methods do not flatten reflections events. Here, we use a four-parameter theory to evaluate these effects and process the data. These four parameters include the PS converted wave stacking velocity （Vc2）, the vertical velocity ratio （Y0）, the effective velocity ratio （Yeff）, and the anisotropy parameter （xoff）, The method utilizes the moveout information at different offsets to estimate the different parameters and ensures that the events are properly aligned for stacking, As a result, this four-parameter theory leads to an improvement in imaging quality and correlation between the P-waves and converted-waves.展开更多
In the present study,the static and dynamic analyses of elliptical functionally graded sandwich(FGS)plates are investigated.The constituent materials of the sandwich plates are ceramic and metal so that the core is ma...In the present study,the static and dynamic analyses of elliptical functionally graded sandwich(FGS)plates are investigated.The constituent materials of the sandwich plates are ceramic and metal so that the core is made of pure metal,while the face sheets consist of a combination of metal and ceramic according to a four-parameter power-law distribution.Different material profiles such as classic,symmetric,and asymmetric can be obtained using the applied generalized power-law distribution relation.The analysis is performed based on the classical laminated plate theory(CLPT)and the Ritz method.The effects of four parameters in the material distribution relation as well as different geometric parameters on the deflection and natural frequencies of elliptical FGS plates are studied.The results of this study show that with a proper distribution of materials,the optimal static and dynamic behavior can be achieved.The results also indicate that the generalized power-law distribution has significant effects on the natural frequencies of elliptical FGS plates.For example,although the frequency parameter of a plate with ceramic face sheets is more than the one with metal face sheets,the use of larger amounts of ceramic does not necessarily increase the natural frequency of the structure.展开更多
Ghana, renowned for its abundant gold reserves, plays a significant role in the global mining industry. Effective management and accurate forecasting of these reserves are vital for sustainable resource utilization an...Ghana, renowned for its abundant gold reserves, plays a significant role in the global mining industry. Effective management and accurate forecasting of these reserves are vital for sustainable resource utilization and economic planning. Forecasting gold reserves and estimating their production lifespan are complex tasks that require robust statistical models capable of capturing the underlying dynamics of gold deposit accumulation and extraction. To this end, the four-parameter Beta distribution function emerges as a promising candidate due to its flexibility and ability to handle non-negative data. This research aims to investigate the fitness and applicability of the four-parameter Beta distribution function for forecasting Ghana’s gold reserves and estimating the production lifespan of this precious resource. The empirical paper relied mainly on quarterly secondary datasets on gold reserve between the years 2009 and 2022 secured from the Minerals Commission of Ghana, Accra. Several known statistical distributions including Beta, Weibull, Normal, Logistic and Gamma were explored with Maximum Likelihood Estimation (MLE) and evaluated using model selection criteria as AIC and BIC. Goodness of Fits were evaluated using Kolmogorov-Smirnov Test (K-S), Cramer-Von Mises Statistic and Anderson-Darling Statistic. Based on the analysis conducted, the four-parameter Beta distribution provided the best fit for gold reserve in Ghana. At a 99.9% confidence level and considering the current annual average gold production estimate of 3,700,031.248 to 4,302,647.888 ounces, the projected lifespan of gold production in Ghana extends to the year 1,953,765. This astounding estimate suggests that the country’s gold reserves are expected to sustain production for an extended period, providing a critical resource for economic development and supporting the mining industry well into the distant future.展开更多
Ghana, renowned for its abundant gold reserves, plays a significant role in the global mining industry. Effective management and accurate forecasting of these reserves are vital for sustainable resource utilization an...Ghana, renowned for its abundant gold reserves, plays a significant role in the global mining industry. Effective management and accurate forecasting of these reserves are vital for sustainable resource utilization and economic planning. Forecasting gold reserves and estimating their production lifespan are complex tasks that require robust statistical models capable of capturing the underlying dynamics of gold deposit accumulation and extraction. To this end, the four-parameter Beta distribution function emerges as a promising candidate due to its flexibility and ability to handle non-negative data. This research aims to investigate the fitness and applicability of the four-parameter Beta distribution function for forecasting Ghana’s gold reserves and estimating the production lifespan of this precious resource. The empirical paper relied mainly on quarterly secondary datasets on gold reserve between the years 2009 and 2022 secured from the Minerals Commission of Ghana, Accra. Several known statistical distributions including Beta, Weibull, Normal, Logistic and Gamma were explored with Maximum Likelihood Estimation (MLE) and evaluated using model selection criteria as AIC and BIC. Goodness of Fits were evaluated using Kolmogorov-Smirnov Test (K-S), Cramer-Von Mises Statistic and Anderson-Darling Statistic. Based on the analysis conducted, the four-parameter Beta distribution provided the best fit for gold reserve in Ghana. At a 99.9% confidence level and considering the current annual average gold production estimate of 3,700,031.248 to 4,302,647.888 ounces, the projected lifespan of gold production in Ghana extends to the year 1,953,765. This astounding estimate suggests that the country’s gold reserves are expected to sustain production for an extended period, providing a critical resource for economic development and supporting the mining industry well into the distant future.展开更多
The catalytic oxidation of HMF involves a cascading reaction with multiple intermediate products,making it crucial to enhance the oriented adsorption capacity of specific functional groups for accelerating the entire ...The catalytic oxidation of HMF involves a cascading reaction with multiple intermediate products,making it crucial to enhance the oriented adsorption capacity of specific functional groups for accelerating the entire process.To achieve the efficient selective oxidation of HMF to FDCA,a series of NiCo_(2)O_(4)catalysts with different morphologies,such as flaky,echinoids,pompon and corolla,were prepared and characterized by XRD,SEM,TEM,BET,XPS,and FTIR.Among the four catalysts,flaky NiCo_(2)O_(4)exhibited the most excellent catalytic activity and stability,with a FDCA yield of 60.1%within 12 h at 80℃without alkali participation.The excellent performance of flaky NiCo_(2)O_(4)catalyst is attributed to the oxygen vacancies and acid sites generated by the exposed(400)facets.The oxygen vacancies and acid sites on the catalyst surface can precisely adsorb-CHO and-CH_(2)-OH of HMF,respectively,and this synergistic effect promotes the efficient production of FDCA.This work is of great significance for fundamentally study the effect of micro-topography or crystal-plane reaction properties on surfaces.展开更多
A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states...A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.展开更多
The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained expe...The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.展开更多
In this paper,we establish a stability estimate for the isoperimetric inequality of horospherically convex domains in hyperbolic plane.This estimate involves a relationship between the Hausdorff distance to a geodesic...In this paper,we establish a stability estimate for the isoperimetric inequality of horospherically convex domains in hyperbolic plane.This estimate involves a relationship between the Hausdorff distance to a geodesic ball and the deficit in the isoperimetric inequality,where the coefficient of the deficit is a universal constant.展开更多
Breast augmentation with implants is a popular cosmetic surgery that enhances breast volume and contour through various placement planes.In this review,we examine the impact of subglandular,subpectoral,and subfascial ...Breast augmentation with implants is a popular cosmetic surgery that enhances breast volume and contour through various placement planes.In this review,we examine the impact of subglandular,subpectoral,and subfascial implant planes on postoperative outcomes and complication rates.Subglandular placement offers simplicity but is associated with higher risks of capsular contracture,hematoma,and rippling in patients with low tissue coverage.The subpectoral plane,widely adopted for its natural appearance and reduced capsular contracture risk,may cause dynamic deformity due to muscle contraction.Although technically challenging,the subfascial plane combines the benefits of soft tissue support and reduced implant displacement.We highlight the importance of choosing an optimal implant plane tailored to each patient’s anatomical and aesthetic needs to enhance surgical outcomes and minimize complications.Further research is needed to validate long-term efficacy,particularly for subfascial placement.展开更多
BACKGROUND The dexmedetomidine(DEX)plus ropivacaine treatment enables a transversus abdominis plane block(TAPB)of the peripheral nerves in patients undergoing radical resection for colorectal cancer(CRC)that can provi...BACKGROUND The dexmedetomidine(DEX)plus ropivacaine treatment enables a transversus abdominis plane block(TAPB)of the peripheral nerves in patients undergoing radical resection for colorectal cancer(CRC)that can provide clinical data for improving the postoperative analgesic effect,reducing the risk of cognitive impairment,and decreasing the circulating levels of serum inflammatory factors and stress hormones.AIM To assess the impact of DEX plus ropivacaine-enabled TAPB on pain,postoperative cognitive dysfunction(POCD),and inflammatory/stress factors.METHODS Our patient cohort was randomly divided into control and observation groups(60/group).The observation group used a DEX plus ropivacaine-enabled TAPB,while the control group employed a ropivacaine-enabled TAPB.The pain score[Visual Analogy Scale(VAS),Montreal Cognitive Assessment(MoCA)],serum inflammatory factor level(C-reactive protein,interleukin-6 and tumor necrosis factor-α),serum stress hormone levels(cortisol and adrenaline)and postoperative adverse reactions were compared between the two groups.RESULTS The observation group VAS scores were lower than those of the control group(better analgesic effect,P<0.05).The MoCA and POCD scores decreased post-surgery in the observation group(P<0.05).In the elderly,the overall VAS and MoCA scores were significantly reduced compared with the young group.The C-reactive protein,interleukin-6,tumor necrosis factor-α,cortisol and adrenaline levels were lower in the observation group compared with the control group post-surgery(P<0.05).There was no significant difference in adverse reactions between the two groups post-surgery,but the incidence of adverse reactions in the observation group was still lower.DEX continuously inhibited p65-phosphorylation levels in the nuclear factorκB pathway at multiple time points,and its inhibitory effect became more significant over time.CONCLUSION DEX plus ropivacaine-enabled TAPB reduces POCD and inflammatory/stress hormone levels,and significantly improves the postoperative analgesic effect of patients undergoing radical resection for colorectal cancer.展开更多
In recent years,the world has seen an exponential increase in energy demand,prompting scientists to look for innovative ways to exploit the power sun’s power.Solar energy technologies use the sun’s energy and light ...In recent years,the world has seen an exponential increase in energy demand,prompting scientists to look for innovative ways to exploit the power sun’s power.Solar energy technologies use the sun’s energy and light to provide heating,lighting,hot water,electricity and even cooling for homes,businesses,and industries.Therefore,ground-level solar radiation data is important for these applications.Thus,our work aims to use a mathematical modeling tool to predict solar irradiation.For this purpose,we are interested in the application of the Adaptive Neuro Fuzzy Inference System.Through this type of artificial neural system,10 models were developed,based on meteorological data such as the Day number(Nj),Ambient temperature(T),Relative Humidity(Hr),Wind speed(WS),Wind direction(WD),Declination(δ),Irradiation outside the atmosphere(Goh),Maximum temperature(Tmax),Minimum temperature(Tmin).These models have been tested by different static indicators to choose the most suitable one for the estimation of the daily global solar radiation.This study led us to choose the M8 model,which takes Nj,T,Hr,δ,Ws,Wd,G0,and S0 as input variables because it presents the best performance either in the learning phase(R^(2)=0.981,RMSE=0.107 kW/m^(2),MAE=0.089 kW/m2)or in the validation phase(R^(2)=0.979,RMSE=0.117 kW/m^(2),MAE=0.101 kW/m^(2)).展开更多
The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compr...The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compression.While previous studies focused on the angleβbetween the maximum principal stress and the structural plane,the role of angleω,between the intermediate principal stress and the structural plane,is often overlooked.Utilizing artificially prefabricated granite specimens with a single non-penetrating structural plane,we set the loading angleβto range from 0°to 90°across seven groups,and assignedωvalues of 0°and 90°in two separate groups.The results show that the peak strength is negatively correlated withβup to 45°,beyond which it tends to stabilize.The angleωexerts a strengthening effect on the peak strength.Deformation mainly occurs post-peak,with the strain values ε_(1) and ε_(3) reaching levels 2−3 times higher than those in intact rock.The structural plane significantly influences failure mode whenω=0°,while failure localizes near the σ_(3) surface of the specimens whenω=90°.The findings enhance data on structural plane rocks under triaxial compression and inform theoretical research,excavation,and support design of rock structures.展开更多
A solution for the lithospheric deformation of a uniform,elastically isotropic layer(EIL)of uniform thickness welded with a uniform,elastically orthotropic half-space(EOHS)due to a vertical tensile line fault(VTLF)wit...A solution for the lithospheric deformation of a uniform,elastically isotropic layer(EIL)of uniform thickness welded with a uniform,elastically orthotropic half-space(EOHS)due to a vertical tensile line fault(VTLF)with an opening in the horizontal direction located in the isotropic layer is derived in the integral form by employing Airy’s stress function approach for the plane strain case.The linear combination of exponential terms appearing in the denominator of the integral expressions of the deformation field of the EIL is expressed as a finite sum of exponential terms(FSET)by applying the method of least squares to analytically compute the deformation field.The displacement field is discussed in detail and computed numerically by considering the EOHS as olivine or barytes material or considering half-space to be isotropic.展开更多
Oxygen evolution reaction(OER) is one of the most important half-reactions related to metal-air batteries,fuel cells, and water-splitting. Due to the sluggish kinetic and multi-electron transfer, catalysts appear to b...Oxygen evolution reaction(OER) is one of the most important half-reactions related to metal-air batteries,fuel cells, and water-splitting. Due to the sluggish kinetic and multi-electron transfer, catalysts appear to be particularly important for the OER. Knowing the reaction mechanism is fundamental to developing new catalysts and improving OER efficiency. In this work, phase transition and atomic reconstruction on Co O(111) plane were revealed through ex-situ diffraction methods and X-ray absorption spectroscopy.At the same time, the electronic state evolution of Co(Ⅱ)/Co(Ⅲ) during the OER process has also been concluded by analyzing the magnetic properties. This work shows that during the OER process, Co(Ⅲ)experiences surface electron rearrangement from IS(intermediate-spin state) to LS(low-spin state) and then returns to IS/HS(high-spin state) under high voltage region. This work provides a new view to reveal the reaction mechanism through the magnetic property and it can be extended to more magnetic 3d transition metals for future catalyst design.展开更多
Aqueous zinc ion batteries(AZIBs)have attracted widespread attention due to their unique advantages.However,the growth of dendrites on the anode and the occurrence of side reactions limits the improvement of electroch...Aqueous zinc ion batteries(AZIBs)have attracted widespread attention due to their unique advantages.However,the growth of dendrites on the anode and the occurrence of side reactions limits the improvement of electrochemical performance of AZIBs.The alloying of zinc anode effectively alleviates above problems,which is beneficial to the long-term cycle performance of AZIBs.In this study,zinc-copper alloy anode(Cu@Zn)was synthesized by melting method.The method is not only simple and easy to operate,but also can make the synthesized anode Cu element uniform distribution and improve the corrosion resistance of the anode.At the same time,the Cu@Zn surface reconstructed has a large proportion of Zn(002)crystal surface exposure,with the zinc affinity of Cu.Both of them can induce the uniform deposition of Zn2+ions along the Zn(002)crystal plane,further inhibiting the growth of dendrite.The Cu@Zn//Cu@Zn symmetrical batteries can cycle more than 1000 times at current densities of 0.3 and 1.2 mA cm^(-2),and maintain a relatively low hysteresis voltage.And the discharge capacity retention rate of Cu@Zn//MnO_(2)maintains 84.64%at 2.0 A g^(-1)after 1000 cycles.This study provides a new methodological reference for the development of advanced AZIBs anodes.展开更多
The effects of the inter-annealing process on the microstructure,plane stress fracture toughness,and tensile properties of an AA7075 cladding sheet were investigated using optical microscopy,scanning electron microsco...The effects of the inter-annealing process on the microstructure,plane stress fracture toughness,and tensile properties of an AA7075 cladding sheet were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,transmission electron microscopy,and mechanical property tests.The results indicate that the plane stress fracture toughness of AA7075-T6 cladding sheet can be greatly improved.The plane stress fracture toughness for the longitudinal-transverse(L-T)and transverse-longitudinal(T-L)directions were 117.7 and 94.8 MPa·m^(1/2),respectively,after intermediate annealing at 380°C.This represents an increase of 23.9 MPa·m^(1/2)in the L-T direction and 22.6 MPa·m^(1/2) in the T-L direction compared with the AA7075-T6 cladding sheet without intermediate annealing.Moreover,the tensile strength remains similar under different conditions.Microstructure analysis indicates that intermediate annealing before heat treatment can result in long sub-grains,few recrystallized grain boundaries,and small size precipitates in AA7075-T6 cladding sheets.展开更多
Extremely large-scale array(XL-array)communications can significantly improve the transmission rate,spectral efficiency,and spatial resolution,and has great potential in next-generation mobile communication networks.A...Extremely large-scale array(XL-array)communications can significantly improve the transmission rate,spectral efficiency,and spatial resolution,and has great potential in next-generation mobile communication networks.A crucial problem in XLarray communications is to determine the boundary of applicable regions of the plane wave model(PWM)and spherical wave model(SWM).In this paper,we propose new PWM/SWM demarcations for XL-arrays from the viewpoint of channel gain and rank.Four sets of results are derived for four different array setups.First,an equi-power line is derived for a point-touniform linear array(ULA)scenario,where an inflection point is found at±π6 central incident angles.Second,an equi-power surface is derived for a point-touniform planar array(UPA)scenario,and it is proved that cos2(ϕ)cos2(φ)=12 is a dividing curve,where ϕ andφdenote the elevation and azimuth angles,respectively.Third,an accurate and explicit expression of the equi-rank surface is obtained for a ULA-to-ULA scenario.Finally,an approximated expression of the equirank surface is obtained for a ULA-to-UPA scenario.With the obtained closed-form expressions,the equirank surface for any antenna structure and any angle can be well estimated.Furthermore,the effect of scatterers is also investigated,from which some insights are drawn.展开更多
During strike-slip fault dislocation,multiple fault planes are commonly observed.The resulting permanent ground deformation can lead to profound structural damage to tunnels.However,existing analytical models do not c...During strike-slip fault dislocation,multiple fault planes are commonly observed.The resulting permanent ground deformation can lead to profound structural damage to tunnels.However,existing analytical models do not consider multiple fault planes.Instead,they concentrate the entire fault displacement onto a single fault plane for analysis,thereby giving rise to notable errors in the calculated results.To address this issue,a refined nonlinear theoretical model was established to analyze the mechanical responses of the tunnels subjected to multiple strike-slip fault dislocations.The analytical model considers the number of fault planes,nonlinear soil‒tunnel interactions,geometric nonlinearity,and fault zone width,leading to a significant improvement in its range of applicability and calculation accuracy.The results of the analytical model are in agreement,both qualitatively and quantitatively,with the model test and numerical results.Then,based on the proposed theoretical model,a sensitivity analysis of parameters was conducted,focusing on the variables such as the number of fault planes,fault plane distance(d),fault displacement ratio(η),burial depth(C),crossing angle(β),tunnel diameter(D),fault zone width(Wf),and strike-slip fault displacement(Δfs).The results show that the peak shear force(Vmax),bending moment(Mmax),and axial force(Nmax)decrease with increasing d.The Vmax of the tunnel is found at the fault plane with the largest fault displacement.C,D,andΔfs contribute to the increases in Vmax,Mmax,and Nmax.Additionally,increasing the number of fault planes reduces Vmax and Mmax,whereas the variation in Nmax remains minimal.展开更多
1 Introduction In highway construction,flled embankments are trapezoidal,and the ground is always improved by sand wells or columns.During embankment construction,because the width and height of the embankment are cha...1 Introduction In highway construction,flled embankments are trapezoidal,and the ground is always improved by sand wells or columns.During embankment construction,because the width and height of the embankment are changing,a non-uniform load that varies with time and lateral location is applied to the underlying ground.The consolidation phenomenon under two-dimensional(2D)conditions will keep pace with the construction of the embankment.In addition,because of evaporation and rainfall,the soils are mostly unsaturated.Therefore,it is meaningful to research the consolidation properties of unsaturated ground under non-uniform loading.展开更多
文摘3-D converted-wave data were acquired using digital MEMS （micro-electromechanical system） three component （3C） sensors in the alternating sand and shale sequence in the overburden of the Shengli Ken-71 area. This gives rise to serious non-hyperbolic moveout effects in the converted-wave data due to both the asymmetrical ray path and anisotropic effects. Conventional velocity analysis and moveout correction based on isotropic methods do not flatten reflections events. Here, we use a four-parameter theory to evaluate these effects and process the data. These four parameters include the PS converted wave stacking velocity （Vc2）, the vertical velocity ratio （Y0）, the effective velocity ratio （Yeff）, and the anisotropy parameter （xoff）, The method utilizes the moveout information at different offsets to estimate the different parameters and ensures that the events are properly aligned for stacking, As a result, this four-parameter theory leads to an improvement in imaging quality and correlation between the P-waves and converted-waves.
文摘In the present study,the static and dynamic analyses of elliptical functionally graded sandwich(FGS)plates are investigated.The constituent materials of the sandwich plates are ceramic and metal so that the core is made of pure metal,while the face sheets consist of a combination of metal and ceramic according to a four-parameter power-law distribution.Different material profiles such as classic,symmetric,and asymmetric can be obtained using the applied generalized power-law distribution relation.The analysis is performed based on the classical laminated plate theory(CLPT)and the Ritz method.The effects of four parameters in the material distribution relation as well as different geometric parameters on the deflection and natural frequencies of elliptical FGS plates are studied.The results of this study show that with a proper distribution of materials,the optimal static and dynamic behavior can be achieved.The results also indicate that the generalized power-law distribution has significant effects on the natural frequencies of elliptical FGS plates.For example,although the frequency parameter of a plate with ceramic face sheets is more than the one with metal face sheets,the use of larger amounts of ceramic does not necessarily increase the natural frequency of the structure.
文摘Ghana, renowned for its abundant gold reserves, plays a significant role in the global mining industry. Effective management and accurate forecasting of these reserves are vital for sustainable resource utilization and economic planning. Forecasting gold reserves and estimating their production lifespan are complex tasks that require robust statistical models capable of capturing the underlying dynamics of gold deposit accumulation and extraction. To this end, the four-parameter Beta distribution function emerges as a promising candidate due to its flexibility and ability to handle non-negative data. This research aims to investigate the fitness and applicability of the four-parameter Beta distribution function for forecasting Ghana’s gold reserves and estimating the production lifespan of this precious resource. The empirical paper relied mainly on quarterly secondary datasets on gold reserve between the years 2009 and 2022 secured from the Minerals Commission of Ghana, Accra. Several known statistical distributions including Beta, Weibull, Normal, Logistic and Gamma were explored with Maximum Likelihood Estimation (MLE) and evaluated using model selection criteria as AIC and BIC. Goodness of Fits were evaluated using Kolmogorov-Smirnov Test (K-S), Cramer-Von Mises Statistic and Anderson-Darling Statistic. Based on the analysis conducted, the four-parameter Beta distribution provided the best fit for gold reserve in Ghana. At a 99.9% confidence level and considering the current annual average gold production estimate of 3,700,031.248 to 4,302,647.888 ounces, the projected lifespan of gold production in Ghana extends to the year 1,953,765. This astounding estimate suggests that the country’s gold reserves are expected to sustain production for an extended period, providing a critical resource for economic development and supporting the mining industry well into the distant future.
文摘Ghana, renowned for its abundant gold reserves, plays a significant role in the global mining industry. Effective management and accurate forecasting of these reserves are vital for sustainable resource utilization and economic planning. Forecasting gold reserves and estimating their production lifespan are complex tasks that require robust statistical models capable of capturing the underlying dynamics of gold deposit accumulation and extraction. To this end, the four-parameter Beta distribution function emerges as a promising candidate due to its flexibility and ability to handle non-negative data. This research aims to investigate the fitness and applicability of the four-parameter Beta distribution function for forecasting Ghana’s gold reserves and estimating the production lifespan of this precious resource. The empirical paper relied mainly on quarterly secondary datasets on gold reserve between the years 2009 and 2022 secured from the Minerals Commission of Ghana, Accra. Several known statistical distributions including Beta, Weibull, Normal, Logistic and Gamma were explored with Maximum Likelihood Estimation (MLE) and evaluated using model selection criteria as AIC and BIC. Goodness of Fits were evaluated using Kolmogorov-Smirnov Test (K-S), Cramer-Von Mises Statistic and Anderson-Darling Statistic. Based on the analysis conducted, the four-parameter Beta distribution provided the best fit for gold reserve in Ghana. At a 99.9% confidence level and considering the current annual average gold production estimate of 3,700,031.248 to 4,302,647.888 ounces, the projected lifespan of gold production in Ghana extends to the year 1,953,765. This astounding estimate suggests that the country’s gold reserves are expected to sustain production for an extended period, providing a critical resource for economic development and supporting the mining industry well into the distant future.
基金supported by the Swedish Energy Agency(P47500-1)the National Key R&D Program of China(2020YFA0710200)+2 种基金the National Natural Science Foundation of China(22378401 and U22A20416)the financial support from STINT(CH2019-8287)financial support from the European Union and Swedish Energy Agency(P2020-90066).
文摘The catalytic oxidation of HMF involves a cascading reaction with multiple intermediate products,making it crucial to enhance the oriented adsorption capacity of specific functional groups for accelerating the entire process.To achieve the efficient selective oxidation of HMF to FDCA,a series of NiCo_(2)O_(4)catalysts with different morphologies,such as flaky,echinoids,pompon and corolla,were prepared and characterized by XRD,SEM,TEM,BET,XPS,and FTIR.Among the four catalysts,flaky NiCo_(2)O_(4)exhibited the most excellent catalytic activity and stability,with a FDCA yield of 60.1%within 12 h at 80℃without alkali participation.The excellent performance of flaky NiCo_(2)O_(4)catalyst is attributed to the oxygen vacancies and acid sites generated by the exposed(400)facets.The oxygen vacancies and acid sites on the catalyst surface can precisely adsorb-CHO and-CH_(2)-OH of HMF,respectively,and this synergistic effect promotes the efficient production of FDCA.This work is of great significance for fundamentally study the effect of micro-topography or crystal-plane reaction properties on surfaces.
基金supports from the National Natural Science Foundation of China (Grant Nos.52004143 and 52374095)the open fund for the Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines (Grant No.SKLMRDPC21KF06).
文摘A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.
文摘The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.
文摘In this paper,we establish a stability estimate for the isoperimetric inequality of horospherically convex domains in hyperbolic plane.This estimate involves a relationship between the Hausdorff distance to a geodesic ball and the deficit in the isoperimetric inequality,where the coefficient of the deficit is a universal constant.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(grant no.LQ22H150005).
文摘Breast augmentation with implants is a popular cosmetic surgery that enhances breast volume and contour through various placement planes.In this review,we examine the impact of subglandular,subpectoral,and subfascial implant planes on postoperative outcomes and complication rates.Subglandular placement offers simplicity but is associated with higher risks of capsular contracture,hematoma,and rippling in patients with low tissue coverage.The subpectoral plane,widely adopted for its natural appearance and reduced capsular contracture risk,may cause dynamic deformity due to muscle contraction.Although technically challenging,the subfascial plane combines the benefits of soft tissue support and reduced implant displacement.We highlight the importance of choosing an optimal implant plane tailored to each patient’s anatomical and aesthetic needs to enhance surgical outcomes and minimize complications.Further research is needed to validate long-term efficacy,particularly for subfascial placement.
文摘BACKGROUND The dexmedetomidine(DEX)plus ropivacaine treatment enables a transversus abdominis plane block(TAPB)of the peripheral nerves in patients undergoing radical resection for colorectal cancer(CRC)that can provide clinical data for improving the postoperative analgesic effect,reducing the risk of cognitive impairment,and decreasing the circulating levels of serum inflammatory factors and stress hormones.AIM To assess the impact of DEX plus ropivacaine-enabled TAPB on pain,postoperative cognitive dysfunction(POCD),and inflammatory/stress factors.METHODS Our patient cohort was randomly divided into control and observation groups(60/group).The observation group used a DEX plus ropivacaine-enabled TAPB,while the control group employed a ropivacaine-enabled TAPB.The pain score[Visual Analogy Scale(VAS),Montreal Cognitive Assessment(MoCA)],serum inflammatory factor level(C-reactive protein,interleukin-6 and tumor necrosis factor-α),serum stress hormone levels(cortisol and adrenaline)and postoperative adverse reactions were compared between the two groups.RESULTS The observation group VAS scores were lower than those of the control group(better analgesic effect,P<0.05).The MoCA and POCD scores decreased post-surgery in the observation group(P<0.05).In the elderly,the overall VAS and MoCA scores were significantly reduced compared with the young group.The C-reactive protein,interleukin-6,tumor necrosis factor-α,cortisol and adrenaline levels were lower in the observation group compared with the control group post-surgery(P<0.05).There was no significant difference in adverse reactions between the two groups post-surgery,but the incidence of adverse reactions in the observation group was still lower.DEX continuously inhibited p65-phosphorylation levels in the nuclear factorκB pathway at multiple time points,and its inhibitory effect became more significant over time.CONCLUSION DEX plus ropivacaine-enabled TAPB reduces POCD and inflammatory/stress hormone levels,and significantly improves the postoperative analgesic effect of patients undergoing radical resection for colorectal cancer.
文摘In recent years,the world has seen an exponential increase in energy demand,prompting scientists to look for innovative ways to exploit the power sun’s power.Solar energy technologies use the sun’s energy and light to provide heating,lighting,hot water,electricity and even cooling for homes,businesses,and industries.Therefore,ground-level solar radiation data is important for these applications.Thus,our work aims to use a mathematical modeling tool to predict solar irradiation.For this purpose,we are interested in the application of the Adaptive Neuro Fuzzy Inference System.Through this type of artificial neural system,10 models were developed,based on meteorological data such as the Day number(Nj),Ambient temperature(T),Relative Humidity(Hr),Wind speed(WS),Wind direction(WD),Declination(δ),Irradiation outside the atmosphere(Goh),Maximum temperature(Tmax),Minimum temperature(Tmin).These models have been tested by different static indicators to choose the most suitable one for the estimation of the daily global solar radiation.This study led us to choose the M8 model,which takes Nj,T,Hr,δ,Ws,Wd,G0,and S0 as input variables because it presents the best performance either in the learning phase(R^(2)=0.981,RMSE=0.107 kW/m^(2),MAE=0.089 kW/m2)or in the validation phase(R^(2)=0.979,RMSE=0.117 kW/m^(2),MAE=0.101 kW/m^(2)).
基金Projects(51979268,52279117,52309146)supported by the National Natural Science Foundation of ChinaProject(SKLGME-JBGS2401)supported by the Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,China。
文摘The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compression.While previous studies focused on the angleβbetween the maximum principal stress and the structural plane,the role of angleω,between the intermediate principal stress and the structural plane,is often overlooked.Utilizing artificially prefabricated granite specimens with a single non-penetrating structural plane,we set the loading angleβto range from 0°to 90°across seven groups,and assignedωvalues of 0°and 90°in two separate groups.The results show that the peak strength is negatively correlated withβup to 45°,beyond which it tends to stabilize.The angleωexerts a strengthening effect on the peak strength.Deformation mainly occurs post-peak,with the strain values ε_(1) and ε_(3) reaching levels 2−3 times higher than those in intact rock.The structural plane significantly influences failure mode whenω=0°,while failure localizes near the σ_(3) surface of the specimens whenω=90°.The findings enhance data on structural plane rocks under triaxial compression and inform theoretical research,excavation,and support design of rock structures.
文摘A solution for the lithospheric deformation of a uniform,elastically isotropic layer(EIL)of uniform thickness welded with a uniform,elastically orthotropic half-space(EOHS)due to a vertical tensile line fault(VTLF)with an opening in the horizontal direction located in the isotropic layer is derived in the integral form by employing Airy’s stress function approach for the plane strain case.The linear combination of exponential terms appearing in the denominator of the integral expressions of the deformation field of the EIL is expressed as a finite sum of exponential terms(FSET)by applying the method of least squares to analytically compute the deformation field.The displacement field is discussed in detail and computed numerically by considering the EOHS as olivine or barytes material or considering half-space to be isotropic.
基金financially supported by the National Natural Science Foundation of China(No.52171210)the Program for the Development of Science and Technology of Jilin Province(Nos.20240101004JC,20220201130GX,and 20240402072GH)。
文摘Oxygen evolution reaction(OER) is one of the most important half-reactions related to metal-air batteries,fuel cells, and water-splitting. Due to the sluggish kinetic and multi-electron transfer, catalysts appear to be particularly important for the OER. Knowing the reaction mechanism is fundamental to developing new catalysts and improving OER efficiency. In this work, phase transition and atomic reconstruction on Co O(111) plane were revealed through ex-situ diffraction methods and X-ray absorption spectroscopy.At the same time, the electronic state evolution of Co(Ⅱ)/Co(Ⅲ) during the OER process has also been concluded by analyzing the magnetic properties. This work shows that during the OER process, Co(Ⅲ)experiences surface electron rearrangement from IS(intermediate-spin state) to LS(low-spin state) and then returns to IS/HS(high-spin state) under high voltage region. This work provides a new view to reveal the reaction mechanism through the magnetic property and it can be extended to more magnetic 3d transition metals for future catalyst design.
基金financially supported by Natural Science Foundation of Hebei Province(Nos.E2024209118,B2022209026)Central Guided Local Science and Technology Development Funding Program(No.246Z4414G)+2 种基金Key Research Project Focused on Basic Research of Hebei Province Education Department(No.JZX2024026)Science and Technology Planning Project of Tangshan City(No.24130217C)Youth Scholars Promotion Plan of North China University of Science and Technology(No.QNTJ202309)
文摘Aqueous zinc ion batteries(AZIBs)have attracted widespread attention due to their unique advantages.However,the growth of dendrites on the anode and the occurrence of side reactions limits the improvement of electrochemical performance of AZIBs.The alloying of zinc anode effectively alleviates above problems,which is beneficial to the long-term cycle performance of AZIBs.In this study,zinc-copper alloy anode(Cu@Zn)was synthesized by melting method.The method is not only simple and easy to operate,but also can make the synthesized anode Cu element uniform distribution and improve the corrosion resistance of the anode.At the same time,the Cu@Zn surface reconstructed has a large proportion of Zn(002)crystal surface exposure,with the zinc affinity of Cu.Both of them can induce the uniform deposition of Zn2+ions along the Zn(002)crystal plane,further inhibiting the growth of dendrite.The Cu@Zn//Cu@Zn symmetrical batteries can cycle more than 1000 times at current densities of 0.3 and 1.2 mA cm^(-2),and maintain a relatively low hysteresis voltage.And the discharge capacity retention rate of Cu@Zn//MnO_(2)maintains 84.64%at 2.0 A g^(-1)after 1000 cycles.This study provides a new methodological reference for the development of advanced AZIBs anodes.
基金the National Key R&D Program of China(Nos.2023YFB3710401,2022YFB3504401)the National Natural Science Foundation of China(Nos.52271094,U1708251)+1 种基金the Key Research and Development Program of Liaoning,China(No.2020JH2/10700003)Qingyuan City Science and Technology Plan Project(No.2023YFJH003),China.
文摘The effects of the inter-annealing process on the microstructure,plane stress fracture toughness,and tensile properties of an AA7075 cladding sheet were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,transmission electron microscopy,and mechanical property tests.The results indicate that the plane stress fracture toughness of AA7075-T6 cladding sheet can be greatly improved.The plane stress fracture toughness for the longitudinal-transverse(L-T)and transverse-longitudinal(T-L)directions were 117.7 and 94.8 MPa·m^(1/2),respectively,after intermediate annealing at 380°C.This represents an increase of 23.9 MPa·m^(1/2)in the L-T direction and 22.6 MPa·m^(1/2) in the T-L direction compared with the AA7075-T6 cladding sheet without intermediate annealing.Moreover,the tensile strength remains similar under different conditions.Microstructure analysis indicates that intermediate annealing before heat treatment can result in long sub-grains,few recrystallized grain boundaries,and small size precipitates in AA7075-T6 cladding sheets.
基金supported in part by the National Natural Science Foundation of China (NSFC) under Grants 62271310 and 62125108in part by the Fundamental Research Funds for the Central Universities of Chinain part by the NSFC under Grant 62431014
文摘Extremely large-scale array(XL-array)communications can significantly improve the transmission rate,spectral efficiency,and spatial resolution,and has great potential in next-generation mobile communication networks.A crucial problem in XLarray communications is to determine the boundary of applicable regions of the plane wave model(PWM)and spherical wave model(SWM).In this paper,we propose new PWM/SWM demarcations for XL-arrays from the viewpoint of channel gain and rank.Four sets of results are derived for four different array setups.First,an equi-power line is derived for a point-touniform linear array(ULA)scenario,where an inflection point is found at±π6 central incident angles.Second,an equi-power surface is derived for a point-touniform planar array(UPA)scenario,and it is proved that cos2(ϕ)cos2(φ)=12 is a dividing curve,where ϕ andφdenote the elevation and azimuth angles,respectively.Third,an accurate and explicit expression of the equi-rank surface is obtained for a ULA-to-ULA scenario.Finally,an approximated expression of the equirank surface is obtained for a ULA-to-UPA scenario.With the obtained closed-form expressions,the equirank surface for any antenna structure and any angle can be well estimated.Furthermore,the effect of scatterers is also investigated,from which some insights are drawn.
基金support from the National Natural Science Foundation of China(Grant Nos.52378411,52208404)China National Railway Group Limited Science and Technology Research and Development Program(Grant No.K2023G041).
文摘During strike-slip fault dislocation,multiple fault planes are commonly observed.The resulting permanent ground deformation can lead to profound structural damage to tunnels.However,existing analytical models do not consider multiple fault planes.Instead,they concentrate the entire fault displacement onto a single fault plane for analysis,thereby giving rise to notable errors in the calculated results.To address this issue,a refined nonlinear theoretical model was established to analyze the mechanical responses of the tunnels subjected to multiple strike-slip fault dislocations.The analytical model considers the number of fault planes,nonlinear soil‒tunnel interactions,geometric nonlinearity,and fault zone width,leading to a significant improvement in its range of applicability and calculation accuracy.The results of the analytical model are in agreement,both qualitatively and quantitatively,with the model test and numerical results.Then,based on the proposed theoretical model,a sensitivity analysis of parameters was conducted,focusing on the variables such as the number of fault planes,fault plane distance(d),fault displacement ratio(η),burial depth(C),crossing angle(β),tunnel diameter(D),fault zone width(Wf),and strike-slip fault displacement(Δfs).The results show that the peak shear force(Vmax),bending moment(Mmax),and axial force(Nmax)decrease with increasing d.The Vmax of the tunnel is found at the fault plane with the largest fault displacement.C,D,andΔfs contribute to the increases in Vmax,Mmax,and Nmax.Additionally,increasing the number of fault planes reduces Vmax and Mmax,whereas the variation in Nmax remains minimal.
基金supported by the National Nature Science Foundation of China(No.12172211)the National Key Research and Development Program of China(No.2019YFC1509800)。
文摘1 Introduction In highway construction,flled embankments are trapezoidal,and the ground is always improved by sand wells or columns.During embankment construction,because the width and height of the embankment are changing,a non-uniform load that varies with time and lateral location is applied to the underlying ground.The consolidation phenomenon under two-dimensional(2D)conditions will keep pace with the construction of the embankment.In addition,because of evaporation and rainfall,the soils are mostly unsaturated.Therefore,it is meaningful to research the consolidation properties of unsaturated ground under non-uniform loading.
