The defence sector is now at an advanced level,catering to the global scenario,and countries also invest heavily in research and development.Countries around the world have spent a lot of money on research and develop...The defence sector is now at an advanced level,catering to the global scenario,and countries also invest heavily in research and development.Countries around the world have spent a lot of money on research and development over the years in order to stay ahead of their competitors.Lightweight materials are critical in defence applications because they allow components to be lighter without sacrificing strength.This review provides an overview of the research related to defence applications.The book provides comprehensive details on current trends in the application of lightweight materials in defence.This review also includes historical and current perspectives on defence technologies.It discusses uses of lightweight materials such as metal matrix composites,polymer composites,ceramic matrix composites,fiber composites in defence sectors Finally,the review paper also emphasizes future military applications of lightweight materials.展开更多
Environmental management of military activities is of growing global concern by defence forces. As one of the largest landholders in Australia, the Australian Defence Force （ADF） is increasingly concerned with susta...Environmental management of military activities is of growing global concern by defence forces. As one of the largest landholders in Australia, the Australian Defence Force （ADF） is increasingly concerned with sustainable environmental management. This paper focuses on how the ADF is maintaining effective environmental management, especially in environmentally sensitive marine protected areas. It uses Shoalwater Bay Training Area （SWBTA） as a research example to examine environmental management strategies conducted by the ADF. SWBTA is one of the most significant Defence training areas in Australia, with a large number of single, joint and combined military exercises conducted in the area. With its maritime component contained in the Great Barrier Reef Marine Park （GBRMP）, the Great Barrier Reef World Heritage Area （GBRWHA）, and abutting Queensland＇s State Marine Parks, it has high protection values. It is therefore vital for the ADF to adopt environmentally responsible management while they are conducting military activities. As to various tools employed to manage environmental performance, the ISO 14001 Environmental Management System （EMS） is widely used by the ADE This paper exanlines military activities and marine environmental management within SWBTA, using the Talisman Saber （TS） exercise series as an example. These are extensive joint exercises conducted by the ADF and the United States defence forces. The paper outlines relevant legislative framework and environmental policies, analyses how the EMS operates in environmental management of military activities, and how military activities comply with these regulations. It discusses the implementation of the ADF EMS, including risk reduction measures, environmental awareness training, consultation and communication with stakeholders. A number of environmental management actions used in the TS exercises are presented to demonstrate the EMS application. Our investigations to this point indicate that the ADF is complying with all relevant legislation and policies. Further research is required to confirm compliance and conclude that military activities have good accord with environmental management objectives.展开更多
This article deals with the relation between ethics and financial and budgetary discipline during economic and social recession in the Czech Republic. We find causes of economic and social recession in the Czech Repub...This article deals with the relation between ethics and financial and budgetary discipline during economic and social recession in the Czech Republic. We find causes of economic and social recession in the Czech Republic in the loss of democratic and human values. Czech Republic was ranked the 57th place in the Corruption Perceptions index 2013 out of the 177 countries assessed, which is the same result achieved by Bahrain, Croatia, and Namibia. Among the 31 European Union （EU） member states and Norway, Switzerland, and Iceland, the Czech Republic is on the 25th site. Market as well as public sector and public finances should follow unwritten rules of ethics and ethical behavior. Such rules should be followed especially by politicians, officials, soldiers, and businessmen. Do we need ethics in present time？ How is the role of the code of ethics in increasing financial and budgetary discipline in the defence sector？ Is it possible to measure efficiency of the code of ethics for financial and budgetary discipline？ We explain the importance of codes of ethics and formulate essential elements that each code of ethics must contain. Next, we deal with the main rules of both financial and budgetary disciplines. Furthermore, this article offers a comparison of several codes of ethics and describes the main problems in our implementation. In the end, we introduce our draft of Code of Ethics for Economic Service Officer in the Ministry of Defence and talk about possible influences of these codes on the quality of employee＇s performance.展开更多
The life of Nitrile Butadiene Rubber(NBR) O-ring seal having shore hardness of A70 and A90 under shock loading conditions was investigated by a specially designed pneumo-hydraulic shock test rig. Shock tests have been...The life of Nitrile Butadiene Rubber(NBR) O-ring seal having shore hardness of A70 and A90 under shock loading conditions was investigated by a specially designed pneumo-hydraulic shock test rig. Shock tests have been carried out on bare seals, seal with conventional polytetrafluoroethylene(PTFE) back-up rings and seal with newly developed carbon composite back-up rings to study its behaviour under different operating conditions until failure. Experiments were conducted by varying annular gap ranging from 0.3 to 0.5 mm, oil temperature from 30 ℃ to 70 ℃ and rate of pressure rise from 600 to 2400 MPa/s. Significant enhancement in seal life was observed with carbon composite back-up ring at reduced annular clearances compared to seal life with conventional PTFE back-up ring and without back-up rings.展开更多
Currently,researchers worldwide are conducting theoretical and experimental studies to understand the significance of nanofluids in heat transfer processes.These fluids are created by dispersing nanoparticles in a bas...Currently,researchers worldwide are conducting theoretical and experimental studies to understand the significance of nanofluids in heat transfer processes.These fluids are created by dispersing nanoparticles in a base fluid.Experiments have demonstrated that nanofluids exhibit superior and more attractive thermal properties compared to conventional fluids.In this current study,we discuss about the heat transfer enhancement of unsteady incompressible laminar couple stress nanofluid flow with Magnetohydrodynamics(MHD)between parallel plates.Prescribed temperature boundary conditions of the surface are employed on the porous surface and it is assumed that the temperature changes periodically over time on the plates.The flow is provoked by periodic suction as well as injection at the plates.With the aid of similarity variables,the system of governing transport equations is transformed into a nonlinear system of ordinary differential equations which is subsequently solved using shooting method along with Runge-Kutta fourth order scheme.The obtained results are shown graphically and explained for the non-dimensional velocity,heat profiles with diverse fluid parameters as well as geometric parameters.Nusselt number is calculated at the lower and upper plates.It is found that temperature component of the fluid is augmenting with suction-injection parameter,whereas it is decreasing in nature with respect to Reynolds number.展开更多
Despite the superior advantages of specific emitter identification in extracting emitter features from in-phase and quadrature(I/Q)signals,challenges persist due to signal-type confusion and background noise interfere...Despite the superior advantages of specific emitter identification in extracting emitter features from in-phase and quadrature(I/Q)signals,challenges persist due to signal-type confusion and background noise interference.To address those limitations,this paper proposes a multi-channel contrast prediction coding and complex-valued residuals network(MCPC-MCVResNet)framework.This model employs contrast prediction techniques to directly extract discriminative features from electromagnetic signal sequences,effectively capturing both amplitude and phase information within I/Q data.A core innovation of this approach is the sphere space softmax(SS-softmax)loss,which optimizes intra-class clustering density of while establishing well-defined boundaries between distinct emitters.The SS-softmax mechanism significantly enhances the model's capacity to discern subtle variations among radiation emitters.Experimental results demonstrate superior identification accuracy,rapid convergence,and exceptional robustness in low signal-to-noise ratio environments.展开更多
This study examines the effect of charge on physical features of a gravastar model in the framework of Rastall gravity.A gravastar is an alternative model to a black hole consisting of three separate regions:the inner...This study examines the effect of charge on physical features of a gravastar model in the framework of Rastall gravity.A gravastar is an alternative model to a black hole consisting of three separate regions:the inner sector,the intermediate shell and the outer sector.Different values of the barotropic equation of state(EoS)parameter provide the mathematical basis for these regions.Field equations(FEs)are initially developed for a spherically symmetric spacetime coupled with charged matter distribution.We then use the temporal component of TolmanⅣspacetime to formulate the radial metric potential for both the inner region and intermediate shell.We also apply the matching criteria to ensure smooth matching of exterior and interior spacetimes so that the constants resulting from integrations can be determined.Afterwards,we explore various physical properties of the developed gravastar model such as the proper length,entropy,energy,and others to analyze how shell thickness and charge affect them.It is concluded that,in the background of Rastall theory,a gravastar model exists and serves as a viable alternative to the black hole.展开更多
Practical applications of smart cities and the Internet of Things(IoT)have multiplied,posing many difficulties in network performance,dependability,and security.Concerns of accessibility,reliability,sustainability,and...Practical applications of smart cities and the Internet of Things(IoT)have multiplied,posing many difficulties in network performance,dependability,and security.Concerns of accessibility,reliability,sustainability,and security too have arisen correspondingly because of the decentralized character of the smart city and IoT systems.Fog computing offers a foundation for various applications,including cognitive support,health and social services,intelligent transportation systems,and pervasive computing and communications.Fog computing can help enhance these apps'productivity and lower the end-to-end delay experienced by such time-sensitive applications.In this research,we propose a reliable and secure service delivery strategy at the network edge for smart cities.To improve the availability and dependability,along with the security of smart city applications,the approach employs a combined method uniting distributed fog servers in addition to mist servers with the help of an intrusion detection system.Simulation findings suggest a reduction of 40.3%in the delay incurred by each service request for highly dense areas and 60.6%for moderately dense environments.Furthermore,the system has low false-negative rates and high detection and accuracy rates,decreasing service requests 2%.展开更多
The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction...The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.展开更多
Friction stir lap welding(FSLW)was adopted to join successfully dissimilar AZ31B Mg alloy and TC4 Ti alloy with Sn foil addition of 30μm thickness.Interfacial microstructure,tensile shear performances and bonding mec...Friction stir lap welding(FSLW)was adopted to join successfully dissimilar AZ31B Mg alloy and TC4 Ti alloy with Sn foil addition of 30μm thickness.Interfacial microstructure,tensile shear performances and bonding mechanism of the joints obtained using three different rotation speeds were studied.High-performance FSLW Mg/Ti dissimilar joints with maximum tensile shear strength of 593.3 N/mm were produced at 1180 r/min,and which was mainly attributed to ultrastrong reaction interlayer consisting of 125.9 nm thick(Mg_(2)Sn+Mg)transition layer and discontinuous(Ti_(6)Sn_(5)+Ti_(3)Al)IMCs layer with 6.58 nm thickness at the interface.The formation of the reaction interlayer was beneficial for high interfacial strength,resulting in significantly improving the joint strength.The fracture of all FSLW joints located on AZ31B Mg stirred zone adjacent to(Mg_(2)Sn+Mg)transition layer or along the crack propagation direction of the AZ31B/TC4 interface with different fracture mechanisms,and which could be consistent with interfacial microstructure.展开更多
An imbalance in adenosine-mediated signaling,particularly the increased A_(2A)R-mediated signaling,plays a role in the pathogenesis of Parkinson's disease.Existing therapeutic approaches fail to alter disease prog...An imbalance in adenosine-mediated signaling,particularly the increased A_(2A)R-mediated signaling,plays a role in the pathogenesis of Parkinson's disease.Existing therapeutic approaches fail to alter disease progression,demonstrating the need for novel approaches in PD.Repetitive transcranial magnetic stimulation is a non-invasive approach that has been shown to improve motor and non-motor symptoms of Parkinson's disease.However,the underlying mechanisms of the beneficial effects of repetitive transcranial magnetic stimulation remain unknown.The purpose of this study is to investigate the extent to which the beneficial effects of prolonged intermittent theta burst stimulation in the 6-hydroxydopamine model of experimental parkinsonism are based on modulation of adenosine-mediated signaling.Animals with unilateral 6-hydroxydopamine lesions underwent intermittent theta burst stimulation for 3 weeks and were tested for motor skills using the Rotarod test.Immunoblot,quantitative reverse transcription polymerase chain reaction,immunohistochemistry,and biochemical analysis of components of adenosine-mediated signaling were performed on the synaptosomal fraction of the lesioned caudate putamen.Prolonged intermittent theta burst stimulation improved motor symptoms in 6-hydroxydopamine-lesioned animals.A 6-hydroxydopamine lesion resulted in progressive loss of dopaminergic neurons in the caudate putamen.Treatment with intermittent theta burst stimulation began 7 days after the lesion,coinciding with the onset of motor symptoms.After treatment with prolonged intermittent theta burst stimulation,complete motor recovery was observed.This improvement was accompanied by downregulation of the e N/CD73-A_(2A)R pathway and a return to physiological levels of A_(1)R-adenosine deaminase 1 after 3 weeks of intermittent theta burst stimulation.Our results demonstrated that 6-hydroxydopamine-induced degeneration reduced the expression of A_(1)R and elevated the expression of A_(2A)R.Intermittent theta burst stimulation reversed these effects by restoring the abundances of A_(1)R and A_(2A)R to control levels.The shift in ARs expression likely restored the balance between dopamine-adenosine signaling,ultimately leading to the recovery of motor control.展开更多
Smart materials with self-healing properties are highly desired.This study investigates graphene-incorporated styrene-isoprene-styrene(SIS)nanocomposites for their self-healing property assisted by Infrared(IR)and mic...Smart materials with self-healing properties are highly desired.This study investigates graphene-incorporated styrene-isoprene-styrene(SIS)nanocomposites for their self-healing property assisted by Infrared(IR)and microwave radiation.The good thermal conductivity and energy-absorbing capacity of graphene offer self-healing capability to SIS/GnP nanocomposites due to their exposure to IR and microwave radiation.The absorbed energy in graphene is transferred to the SIS matrix,facilitating the diffusion,re-entanglement,and restoration of the SIS polymer chains,resulting in multiple times self-healing capabilities using various external stimuli.All SIS/GnP nanocomposite samples exhibit self-healing behavior,and the healing efficiency rises with increasing GnP content in the nanocomposites and healing time.The cut mark on the SIS/GnP nanocomposite sample(having 10 wt.%of GnP)entirely disappears when the sample is placed in contact with IR radiation(at 250 W)for 10 min.In addition,the sample is completely healed when exposed to microwave radiation(at 900 W)for less than 30 s.The good dispersion of the graphene nanoplates in the SIS matrix was observed in SEM micrographs.Strong interfacial interactions between the SIS copolymer chains and exfoliated graphene(GnP)due toπ-πstacking stabilize graphene dispersion against agglomeration.The effect of graphene nanoplates on the SIS thermoplastic elastomer’s thermal stability and phase transition is also studied by Thermo-gravimetric analysis(TGA)and Differential Scanning Calorimetry(DSC)analysis.展开更多
Sliding electrical contact is a common phenomenon in electrical equipment and affects performance.In this paper,the mechanism of sliding electric contact pair transition and the moment when transition occurs are inves...Sliding electrical contact is a common phenomenon in electrical equipment and affects performance.In this paper,the mechanism of sliding electric contact pair transition and the moment when transition occurs are investigated using the railgun as an example.Transition is the phenomenon where the contact between the armature and rails changes from solid-solid contact to solid-arc-solid contact.In this paper,the finite element-boundary element coupling method(FE-BE method)is used to simulate the process of armature movement.Then,the force,thermal,and electrical parameters on the armature/rail contact surface are analyzed to explore the development of contact separation.Finally,the occurrence of the transition is judged based on the Townsend discharge model(improved by Rogowski).A Small-caliber railgun firing test was carried out to validate the methodology presented in this paper.Results show that the drop edge of the current will result in the armature/rail not being able to make full contact,and the contact gap may break down,leading to a sharp increase in contact resistance and deterioration of railgun performance.Judging the occurrence of transition based on the evolution of the contact gap and the Townsend discharge model is reliable.The research provides new ideas for studying railgun transition and sliding electric contact failure.展开更多
Merged satellite altimeter products are widely used in ocean-related fields.Currently,the altimeter merged products of archiving validation and interpretation of satellite oceanographic(AVISO)data are widely used inte...Merged satellite altimeter products are widely used in ocean-related fields.Currently,the altimeter merged products of archiving validation and interpretation of satellite oceanographic(AVISO)data are widely used internationally.Chinese National Satellite Ocean Application Service also released merged altimeter products(ALT MUL)in 2023.However,there are few studies on the quality assessment of ALT MUL.Based on the data of AVISO merged products,Jason3 satellite,tide gauge and drifter buoy,the quality assessment and effect analysis of ALT MUL merged products were carried out by means of error evaluation index,interpolation along rails,velocity inversion and power spectrum.The result shows that the average sea level anomaly(SLA)of ALT MUL is about 2 cm smaller than that of AVISO.And they are consistent with the large-scale characteristics and spatial distribution.These two SLA products are both in accordance with normal distribution.Results indicate a lesser congruence between ALT MUL and Jason3 satellite compared to AVISO.This difference may be attributed to the fact that AVISO products use Jason3 satellite as crosscalibrated reference satellite during the merged process.Comparing the matching effect of the two merged products with the tide gauge and drifter buoy,ALT MUL merged products are superior to AVISO in general.The energy spectral density was calculated by using Jason3 satellite data along the orbit,and the two merged products were interpolated to the data points along the orbit.The effective resolution of AVISO and ALT MUL merged products was 180 km and 210 km respectively through spectral calculation,indicating that AVISO merged products have higher effective resolution.展开更多
Rotary friction welding is a highly effective solid-state technique for joining dissimilar materials,which offers the potential for significant weight reduction without compromising strength.Traditionally,during rotar...Rotary friction welding is a highly effective solid-state technique for joining dissimilar materials,which offers the potential for significant weight reduction without compromising strength.Traditionally,during rotary friction welding,the severely deformed material,or flash,is expelled from the interface and machined away to achieve the desired joint geometry.However,this work introduces a novel approach:trapping the flash within the joint to improve joint properties.The study investigates two different interface geometry combinationsdflat-flat and flat-taper interfaces.Previous research shows that Ni interlayer between steel and titanium can enhance the joint strength.This study builds on the existing knowledge(effect of Ni interlayer)by examining the influence of interface geometry to further improve the dissimilar joint performance.The experimental results,including tensile testing and microstructural characterization,highlight the superior performance of the flat-taper interface.The modified geometry minimizes flash loss,providing a cavity that retains both the flash and the Ni interlayer within the joint.This retention promotes dynamic recrystallization,resulting in refined grain structures near the interface.Moreover,the trapped Ni interlayer effectively prevents the formation of brittle Fe-Ti intermetallic compounds at the dissimilar material interface.The findings reveal that the flat-taper interface improved joint strength by an impressive 105%compared to the flat-flat interface.This innovative geometry modification demonstrates the potential to enhance mechanical properties of dissimilar joints through better flash and interlayer management.展开更多
This study explores the impact of bismuth oxide(Bi_(2)O_(3))on the optical and radiation shielding properties of transparent,lead-free thulium-doped bismuth borotellurite radiation shielding glass.The investigated gla...This study explores the impact of bismuth oxide(Bi_(2)O_(3))on the optical and radiation shielding properties of transparent,lead-free thulium-doped bismuth borotellurite radiation shielding glass.The investigated glass composition follows the formula[(TeO_(2))_(75)(B_(2)O_(3))_(25)]_(98-x)(Bi_(2)O_(3))_x[Tm_(2)O_(3)]_(2),where x=0 mol%,5 mol%,10 mol%,15 mol%,20 mol%,25 mol%,and 30 mol%.All glass samples remain transparent,with an optical bandgap(E_(opt))exceeding 3.1 e V,ensuring visible light transmission.Radiation shielding data from Phy-X and XCom reveal interactions of the photoelectric effect,Compton scattering,and pair production,with minimal relative difference in mass attenuation coefficient(MAC)which is between0.05 and 0.56.At 0.662 Me V photon energy,the 20 mol%and 25 mol%Bi_(2)O_(3)glasses exhibit significantly higher Phy-X MAC values than other samples,except RS 520 glass,which contains 71%Pb O.Despite incorporating only up to 25 mol%Bi_(2)O_(3),these glasses outperform others in density,half-value layer(HVL),and mean free path(MFP).Correlating E_(opt)and MAC,the 20 mol%Bi_(2)O_(3)glass is the best candidate for transparent radiation shielding glass due to its wide optical bandgap which prevents ionization of trapped holes.Significantly,the linkage between MFP and molar refraction was also discovered based on the particle size influence on both parameters.展开更多
Background: Undergoing ultrasound scanning (USS) during the first trimester of pregnancy is highly imperative for expecting mothers, as it supports the early detection of any malformations, identifying the fetal numbe...Background: Undergoing ultrasound scanning (USS) during the first trimester of pregnancy is highly imperative for expecting mothers, as it supports the early detection of any malformations, identifying the fetal number, fetal growth, fetal sex, and calculation of delivery. Previous studies have shown that undergoing such prenatal screening procedures could reduce the antenatal anxiety levels of expectant mothers. The present study aimed to explore the impact of first-trimester ultrasound scanning towards the antenatal anxiety and identify the predictors of antenatal anxiety among expectant mothers in the first trimester. Methods: A repeated measure design study was conducted in Maternity Clinics of University Hospital KDU, Ninewells Care Hospital and Navy General Hospital over 4 months with one hundred and fifteen (n = 115) expectant mothers. Participants completed a general information sheet first and State Trait Anxiety Inventory (STAI) (Spielberger et al., 1970) was administered before and after undergoing the USS. Results: Mean age of the participants was 28.84 ± 3.68. The Wilcoxon Signed Rank test showed that there is a significant reduction of participants’ antenatal anxiety levels following the USS z = −5.658, p Conclusions: Findings suggest that undergoing the first trimester USS significantly reduces the antenatal state anxiety and partner’s support is an important factor in reducing the antenatal anxiety experienced by expectant mothers in the first trimester. Future studies can focus on how USS can contribute to alleviating antenatal anxiety in second and third trimesters.展开更多
To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.T...To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.The methods currently used for measuring dose rates are inadequate for obtaining the dose rates of key radionuclides and have large angular response errors when monitoring surface sources.To address this practical problem,this study proposes three methods for measuring the dose rate:the weighted peak total ratio,mean value regression,and numerical integration methods.These methods are based on energy-spectrum measurement data,and they were theoretically derived and numerically evaluated.Finally,a 1-m-long hexagonal radioactive surface source was integrated into a larger surface source.In situ measurement experiments were conducted on a large radioactive surface source using a dose-rate meter and a portable HPGespectrometer to analyze the errors of the three aforementioned methods and verify their validity.展开更多
文摘The defence sector is now at an advanced level,catering to the global scenario,and countries also invest heavily in research and development.Countries around the world have spent a lot of money on research and development over the years in order to stay ahead of their competitors.Lightweight materials are critical in defence applications because they allow components to be lighter without sacrificing strength.This review provides an overview of the research related to defence applications.The book provides comprehensive details on current trends in the application of lightweight materials in defence.This review also includes historical and current perspectives on defence technologies.It discusses uses of lightweight materials such as metal matrix composites,polymer composites,ceramic matrix composites,fiber composites in defence sectors Finally,the review paper also emphasizes future military applications of lightweight materials.
文摘Environmental management of military activities is of growing global concern by defence forces. As one of the largest landholders in Australia, the Australian Defence Force （ADF） is increasingly concerned with sustainable environmental management. This paper focuses on how the ADF is maintaining effective environmental management, especially in environmentally sensitive marine protected areas. It uses Shoalwater Bay Training Area （SWBTA） as a research example to examine environmental management strategies conducted by the ADF. SWBTA is one of the most significant Defence training areas in Australia, with a large number of single, joint and combined military exercises conducted in the area. With its maritime component contained in the Great Barrier Reef Marine Park （GBRMP）, the Great Barrier Reef World Heritage Area （GBRWHA）, and abutting Queensland＇s State Marine Parks, it has high protection values. It is therefore vital for the ADF to adopt environmentally responsible management while they are conducting military activities. As to various tools employed to manage environmental performance, the ISO 14001 Environmental Management System （EMS） is widely used by the ADE This paper exanlines military activities and marine environmental management within SWBTA, using the Talisman Saber （TS） exercise series as an example. These are extensive joint exercises conducted by the ADF and the United States defence forces. The paper outlines relevant legislative framework and environmental policies, analyses how the EMS operates in environmental management of military activities, and how military activities comply with these regulations. It discusses the implementation of the ADF EMS, including risk reduction measures, environmental awareness training, consultation and communication with stakeholders. A number of environmental management actions used in the TS exercises are presented to demonstrate the EMS application. Our investigations to this point indicate that the ADF is complying with all relevant legislation and policies. Further research is required to confirm compliance and conclude that military activities have good accord with environmental management objectives.
文摘This article deals with the relation between ethics and financial and budgetary discipline during economic and social recession in the Czech Republic. We find causes of economic and social recession in the Czech Republic in the loss of democratic and human values. Czech Republic was ranked the 57th place in the Corruption Perceptions index 2013 out of the 177 countries assessed, which is the same result achieved by Bahrain, Croatia, and Namibia. Among the 31 European Union （EU） member states and Norway, Switzerland, and Iceland, the Czech Republic is on the 25th site. Market as well as public sector and public finances should follow unwritten rules of ethics and ethical behavior. Such rules should be followed especially by politicians, officials, soldiers, and businessmen. Do we need ethics in present time？ How is the role of the code of ethics in increasing financial and budgetary discipline in the defence sector？ Is it possible to measure efficiency of the code of ethics for financial and budgetary discipline？ We explain the importance of codes of ethics and formulate essential elements that each code of ethics must contain. Next, we deal with the main rules of both financial and budgetary disciplines. Furthermore, this article offers a comparison of several codes of ethics and describes the main problems in our implementation. In the end, we introduce our draft of Code of Ethics for Economic Service Officer in the Ministry of Defence and talk about possible influences of these codes on the quality of employee＇s performance.
文摘The life of Nitrile Butadiene Rubber(NBR) O-ring seal having shore hardness of A70 and A90 under shock loading conditions was investigated by a specially designed pneumo-hydraulic shock test rig. Shock tests have been carried out on bare seals, seal with conventional polytetrafluoroethylene(PTFE) back-up rings and seal with newly developed carbon composite back-up rings to study its behaviour under different operating conditions until failure. Experiments were conducted by varying annular gap ranging from 0.3 to 0.5 mm, oil temperature from 30 ℃ to 70 ℃ and rate of pressure rise from 600 to 2400 MPa/s. Significant enhancement in seal life was observed with carbon composite back-up ring at reduced annular clearances compared to seal life with conventional PTFE back-up ring and without back-up rings.
文摘Currently,researchers worldwide are conducting theoretical and experimental studies to understand the significance of nanofluids in heat transfer processes.These fluids are created by dispersing nanoparticles in a base fluid.Experiments have demonstrated that nanofluids exhibit superior and more attractive thermal properties compared to conventional fluids.In this current study,we discuss about the heat transfer enhancement of unsteady incompressible laminar couple stress nanofluid flow with Magnetohydrodynamics(MHD)between parallel plates.Prescribed temperature boundary conditions of the surface are employed on the porous surface and it is assumed that the temperature changes periodically over time on the plates.The flow is provoked by periodic suction as well as injection at the plates.With the aid of similarity variables,the system of governing transport equations is transformed into a nonlinear system of ordinary differential equations which is subsequently solved using shooting method along with Runge-Kutta fourth order scheme.The obtained results are shown graphically and explained for the non-dimensional velocity,heat profiles with diverse fluid parameters as well as geometric parameters.Nusselt number is calculated at the lower and upper plates.It is found that temperature component of the fluid is augmenting with suction-injection parameter,whereas it is decreasing in nature with respect to Reynolds number.
基金supported by the National Natural Science Foundation of China(62201602)。
文摘Despite the superior advantages of specific emitter identification in extracting emitter features from in-phase and quadrature(I/Q)signals,challenges persist due to signal-type confusion and background noise interference.To address those limitations,this paper proposes a multi-channel contrast prediction coding and complex-valued residuals network(MCPC-MCVResNet)framework.This model employs contrast prediction techniques to directly extract discriminative features from electromagnetic signal sequences,effectively capturing both amplitude and phase information within I/Q data.A core innovation of this approach is the sphere space softmax(SS-softmax)loss,which optimizes intra-class clustering density of while establishing well-defined boundaries between distinct emitters.The SS-softmax mechanism significantly enhances the model's capacity to discern subtle variations among radiation emitters.Experimental results demonstrate superior identification accuracy,rapid convergence,and exceptional robustness in low signal-to-noise ratio environments.
文摘This study examines the effect of charge on physical features of a gravastar model in the framework of Rastall gravity.A gravastar is an alternative model to a black hole consisting of three separate regions:the inner sector,the intermediate shell and the outer sector.Different values of the barotropic equation of state(EoS)parameter provide the mathematical basis for these regions.Field equations(FEs)are initially developed for a spherically symmetric spacetime coupled with charged matter distribution.We then use the temporal component of TolmanⅣspacetime to formulate the radial metric potential for both the inner region and intermediate shell.We also apply the matching criteria to ensure smooth matching of exterior and interior spacetimes so that the constants resulting from integrations can be determined.Afterwards,we explore various physical properties of the developed gravastar model such as the proper length,entropy,energy,and others to analyze how shell thickness and charge affect them.It is concluded that,in the background of Rastall theory,a gravastar model exists and serves as a viable alternative to the black hole.
基金co-funded by the European Union under the REFRESH-Research Excellence For REgion Sustainability and High-tech Industries project number CZ.10.03.01/00/22_003/0000048 via the Operational Programme Just Transitionsupported by the Ministry of Education,Youth and Sports of the Czech Republic conducted by VSB-Technical University of Ostrava,Czechia,under Grants SP2025/021 and SP2025/039。
文摘Practical applications of smart cities and the Internet of Things(IoT)have multiplied,posing many difficulties in network performance,dependability,and security.Concerns of accessibility,reliability,sustainability,and security too have arisen correspondingly because of the decentralized character of the smart city and IoT systems.Fog computing offers a foundation for various applications,including cognitive support,health and social services,intelligent transportation systems,and pervasive computing and communications.Fog computing can help enhance these apps'productivity and lower the end-to-end delay experienced by such time-sensitive applications.In this research,we propose a reliable and secure service delivery strategy at the network edge for smart cities.To improve the availability and dependability,along with the security of smart city applications,the approach employs a combined method uniting distributed fog servers in addition to mist servers with the help of an intrusion detection system.Simulation findings suggest a reduction of 40.3%in the delay incurred by each service request for highly dense areas and 60.6%for moderately dense environments.Furthermore,the system has low false-negative rates and high detection and accuracy rates,decreasing service requests 2%.
基金supported by the Istanbul Technical University Office of Scientific Research Projects(ITUBAPSIS),under grant MYL-2022-43776。
文摘The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.52005240,52164045)Young Talent Program of Major Disciplines of Academic and Technical Leaders in Jiangxi Province(No.20212BCJ23028)Outstanding Youth Foundation in Jiangxi Province(No.20224ACB214012).
文摘Friction stir lap welding(FSLW)was adopted to join successfully dissimilar AZ31B Mg alloy and TC4 Ti alloy with Sn foil addition of 30μm thickness.Interfacial microstructure,tensile shear performances and bonding mechanism of the joints obtained using three different rotation speeds were studied.High-performance FSLW Mg/Ti dissimilar joints with maximum tensile shear strength of 593.3 N/mm were produced at 1180 r/min,and which was mainly attributed to ultrastrong reaction interlayer consisting of 125.9 nm thick(Mg_(2)Sn+Mg)transition layer and discontinuous(Ti_(6)Sn_(5)+Ti_(3)Al)IMCs layer with 6.58 nm thickness at the interface.The formation of the reaction interlayer was beneficial for high interfacial strength,resulting in significantly improving the joint strength.The fracture of all FSLW joints located on AZ31B Mg stirred zone adjacent to(Mg_(2)Sn+Mg)transition layer or along the crack propagation direction of the AZ31B/TC4 interface with different fracture mechanisms,and which could be consistent with interfacial microstructure.
基金supported by a grant from Ministry of Science,Technological Development and Innovation,Serbia,No.451-03-68/2022-14/200178(to NN)University of Defence,No.MFVMA/02/22-24(to MN)。
文摘An imbalance in adenosine-mediated signaling,particularly the increased A_(2A)R-mediated signaling,plays a role in the pathogenesis of Parkinson's disease.Existing therapeutic approaches fail to alter disease progression,demonstrating the need for novel approaches in PD.Repetitive transcranial magnetic stimulation is a non-invasive approach that has been shown to improve motor and non-motor symptoms of Parkinson's disease.However,the underlying mechanisms of the beneficial effects of repetitive transcranial magnetic stimulation remain unknown.The purpose of this study is to investigate the extent to which the beneficial effects of prolonged intermittent theta burst stimulation in the 6-hydroxydopamine model of experimental parkinsonism are based on modulation of adenosine-mediated signaling.Animals with unilateral 6-hydroxydopamine lesions underwent intermittent theta burst stimulation for 3 weeks and were tested for motor skills using the Rotarod test.Immunoblot,quantitative reverse transcription polymerase chain reaction,immunohistochemistry,and biochemical analysis of components of adenosine-mediated signaling were performed on the synaptosomal fraction of the lesioned caudate putamen.Prolonged intermittent theta burst stimulation improved motor symptoms in 6-hydroxydopamine-lesioned animals.A 6-hydroxydopamine lesion resulted in progressive loss of dopaminergic neurons in the caudate putamen.Treatment with intermittent theta burst stimulation began 7 days after the lesion,coinciding with the onset of motor symptoms.After treatment with prolonged intermittent theta burst stimulation,complete motor recovery was observed.This improvement was accompanied by downregulation of the e N/CD73-A_(2A)R pathway and a return to physiological levels of A_(1)R-adenosine deaminase 1 after 3 weeks of intermittent theta burst stimulation.Our results demonstrated that 6-hydroxydopamine-induced degeneration reduced the expression of A_(1)R and elevated the expression of A_(2A)R.Intermittent theta burst stimulation reversed these effects by restoring the abundances of A_(1)R and A_(2A)R to control levels.The shift in ARs expression likely restored the balance between dopamine-adenosine signaling,ultimately leading to the recovery of motor control.
文摘Smart materials with self-healing properties are highly desired.This study investigates graphene-incorporated styrene-isoprene-styrene(SIS)nanocomposites for their self-healing property assisted by Infrared(IR)and microwave radiation.The good thermal conductivity and energy-absorbing capacity of graphene offer self-healing capability to SIS/GnP nanocomposites due to their exposure to IR and microwave radiation.The absorbed energy in graphene is transferred to the SIS matrix,facilitating the diffusion,re-entanglement,and restoration of the SIS polymer chains,resulting in multiple times self-healing capabilities using various external stimuli.All SIS/GnP nanocomposite samples exhibit self-healing behavior,and the healing efficiency rises with increasing GnP content in the nanocomposites and healing time.The cut mark on the SIS/GnP nanocomposite sample(having 10 wt.%of GnP)entirely disappears when the sample is placed in contact with IR radiation(at 250 W)for 10 min.In addition,the sample is completely healed when exposed to microwave radiation(at 900 W)for less than 30 s.The good dispersion of the graphene nanoplates in the SIS matrix was observed in SEM micrographs.Strong interfacial interactions between the SIS copolymer chains and exfoliated graphene(GnP)due toπ-πstacking stabilize graphene dispersion against agglomeration.The effect of graphene nanoplates on the SIS thermoplastic elastomer’s thermal stability and phase transition is also studied by Thermo-gravimetric analysis(TGA)and Differential Scanning Calorimetry(DSC)analysis.
文摘Sliding electrical contact is a common phenomenon in electrical equipment and affects performance.In this paper,the mechanism of sliding electric contact pair transition and the moment when transition occurs are investigated using the railgun as an example.Transition is the phenomenon where the contact between the armature and rails changes from solid-solid contact to solid-arc-solid contact.In this paper,the finite element-boundary element coupling method(FE-BE method)is used to simulate the process of armature movement.Then,the force,thermal,and electrical parameters on the armature/rail contact surface are analyzed to explore the development of contact separation.Finally,the occurrence of the transition is judged based on the Townsend discharge model(improved by Rogowski).A Small-caliber railgun firing test was carried out to validate the methodology presented in this paper.Results show that the drop edge of the current will result in the armature/rail not being able to make full contact,and the contact gap may break down,leading to a sharp increase in contact resistance and deterioration of railgun performance.Judging the occurrence of transition based on the evolution of the contact gap and the Townsend discharge model is reliable.The research provides new ideas for studying railgun transition and sliding electric contact failure.
基金The National Key R&D Program of China under contract No.2021YFC3101503the National Natural Science Foundation of China under contract Nos 42276205 and 42406195+1 种基金the Hunan Provincial Natural Science Foundation of China under contract No.2023JJ10053the Youth Independent Innovation Science Foundation under contract No.ZK24-54.
文摘Merged satellite altimeter products are widely used in ocean-related fields.Currently,the altimeter merged products of archiving validation and interpretation of satellite oceanographic(AVISO)data are widely used internationally.Chinese National Satellite Ocean Application Service also released merged altimeter products(ALT MUL)in 2023.However,there are few studies on the quality assessment of ALT MUL.Based on the data of AVISO merged products,Jason3 satellite,tide gauge and drifter buoy,the quality assessment and effect analysis of ALT MUL merged products were carried out by means of error evaluation index,interpolation along rails,velocity inversion and power spectrum.The result shows that the average sea level anomaly(SLA)of ALT MUL is about 2 cm smaller than that of AVISO.And they are consistent with the large-scale characteristics and spatial distribution.These two SLA products are both in accordance with normal distribution.Results indicate a lesser congruence between ALT MUL and Jason3 satellite compared to AVISO.This difference may be attributed to the fact that AVISO products use Jason3 satellite as crosscalibrated reference satellite during the merged process.Comparing the matching effect of the two merged products with the tide gauge and drifter buoy,ALT MUL merged products are superior to AVISO in general.The energy spectral density was calculated by using Jason3 satellite data along the orbit,and the two merged products were interpolated to the data points along the orbit.The effective resolution of AVISO and ALT MUL merged products was 180 km and 210 km respectively through spectral calculation,indicating that AVISO merged products have higher effective resolution.
文摘Rotary friction welding is a highly effective solid-state technique for joining dissimilar materials,which offers the potential for significant weight reduction without compromising strength.Traditionally,during rotary friction welding,the severely deformed material,or flash,is expelled from the interface and machined away to achieve the desired joint geometry.However,this work introduces a novel approach:trapping the flash within the joint to improve joint properties.The study investigates two different interface geometry combinationsdflat-flat and flat-taper interfaces.Previous research shows that Ni interlayer between steel and titanium can enhance the joint strength.This study builds on the existing knowledge(effect of Ni interlayer)by examining the influence of interface geometry to further improve the dissimilar joint performance.The experimental results,including tensile testing and microstructural characterization,highlight the superior performance of the flat-taper interface.The modified geometry minimizes flash loss,providing a cavity that retains both the flash and the Ni interlayer within the joint.This retention promotes dynamic recrystallization,resulting in refined grain structures near the interface.Moreover,the trapped Ni interlayer effectively prevents the formation of brittle Fe-Ti intermetallic compounds at the dissimilar material interface.The findings reveal that the flat-taper interface improved joint strength by an impressive 105%compared to the flat-flat interface.This innovative geometry modification demonstrates the potential to enhance mechanical properties of dissimilar joints through better flash and interlayer management.
基金funded by the National Defence University of Malaysia(Grant No.UPNM/2022/GPJP/SG/3)My Brain Sc Scholarship 2023。
文摘This study explores the impact of bismuth oxide(Bi_(2)O_(3))on the optical and radiation shielding properties of transparent,lead-free thulium-doped bismuth borotellurite radiation shielding glass.The investigated glass composition follows the formula[(TeO_(2))_(75)(B_(2)O_(3))_(25)]_(98-x)(Bi_(2)O_(3))_x[Tm_(2)O_(3)]_(2),where x=0 mol%,5 mol%,10 mol%,15 mol%,20 mol%,25 mol%,and 30 mol%.All glass samples remain transparent,with an optical bandgap(E_(opt))exceeding 3.1 e V,ensuring visible light transmission.Radiation shielding data from Phy-X and XCom reveal interactions of the photoelectric effect,Compton scattering,and pair production,with minimal relative difference in mass attenuation coefficient(MAC)which is between0.05 and 0.56.At 0.662 Me V photon energy,the 20 mol%and 25 mol%Bi_(2)O_(3)glasses exhibit significantly higher Phy-X MAC values than other samples,except RS 520 glass,which contains 71%Pb O.Despite incorporating only up to 25 mol%Bi_(2)O_(3),these glasses outperform others in density,half-value layer(HVL),and mean free path(MFP).Correlating E_(opt)and MAC,the 20 mol%Bi_(2)O_(3)glass is the best candidate for transparent radiation shielding glass due to its wide optical bandgap which prevents ionization of trapped holes.Significantly,the linkage between MFP and molar refraction was also discovered based on the particle size influence on both parameters.
文摘Background: Undergoing ultrasound scanning (USS) during the first trimester of pregnancy is highly imperative for expecting mothers, as it supports the early detection of any malformations, identifying the fetal number, fetal growth, fetal sex, and calculation of delivery. Previous studies have shown that undergoing such prenatal screening procedures could reduce the antenatal anxiety levels of expectant mothers. The present study aimed to explore the impact of first-trimester ultrasound scanning towards the antenatal anxiety and identify the predictors of antenatal anxiety among expectant mothers in the first trimester. Methods: A repeated measure design study was conducted in Maternity Clinics of University Hospital KDU, Ninewells Care Hospital and Navy General Hospital over 4 months with one hundred and fifteen (n = 115) expectant mothers. Participants completed a general information sheet first and State Trait Anxiety Inventory (STAI) (Spielberger et al., 1970) was administered before and after undergoing the USS. Results: Mean age of the participants was 28.84 ± 3.68. The Wilcoxon Signed Rank test showed that there is a significant reduction of participants’ antenatal anxiety levels following the USS z = −5.658, p Conclusions: Findings suggest that undergoing the first trimester USS significantly reduces the antenatal state anxiety and partner’s support is an important factor in reducing the antenatal anxiety experienced by expectant mothers in the first trimester. Future studies can focus on how USS can contribute to alleviating antenatal anxiety in second and third trimesters.
文摘To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.The methods currently used for measuring dose rates are inadequate for obtaining the dose rates of key radionuclides and have large angular response errors when monitoring surface sources.To address this practical problem,this study proposes three methods for measuring the dose rate:the weighted peak total ratio,mean value regression,and numerical integration methods.These methods are based on energy-spectrum measurement data,and they were theoretically derived and numerically evaluated.Finally,a 1-m-long hexagonal radioactive surface source was integrated into a larger surface source.In situ measurement experiments were conducted on a large radioactive surface source using a dose-rate meter and a portable HPGespectrometer to analyze the errors of the three aforementioned methods and verify their validity.
