Attitude pursuit guidance law is suitable for low cost missiles.A strap-down seeker is used to achieve this guidance law.The additional angles of attack or sideslip caused by wind and by control system are considered ...Attitude pursuit guidance law is suitable for low cost missiles.A strap-down seeker is used to achieve this guidance law.The additional angles of attack or sideslip caused by wind and by control system are considered as two disturbing factors which make attitude pursuit law impossible.Therefore,general attitude pursuit guidance law did not account for this two disturbing factors,because with those disturbing factors,it is difficult to apply.To solve the problem,the principle of strap-down seeker detecting target is investigated,the mathematical control model is established,then a modified attitude pursuit guidance law which employs the angular correction for those two disturbing factors is presented.It is proved that the modified attitude pursuit guidance law is appropriated to both in the presence of the additional angle of attack or sideslip via the simulations with the mathematical control model and Monte-Carlo method.展开更多
Social gender theory emphasizes that gender is a cultural construct,and thus self-evaluations in the job application process inevitably differ between men and women.This study analyzes the online resumes of job seeker...Social gender theory emphasizes that gender is a cultural construct,and thus self-evaluations in the job application process inevitably differ between men and women.This study analyzes the online resumes of job seekers from several technologybased companies in Chengdu,Sichuan Province,and finds the following:1.Compared to men,women are more likely to highlight their learning ability,positive personality,sense of responsibility,communication skills,teamwork ability,adaptability,and past experiences or certifications in their self-evaluations.2.In contrast,men are more likely than women to emphasize their hardworking attitude in their self-evaluations.3.There are no significant gender differences in the presentation of self-assessment on stress resistance and execution ability.This study highlights gender differences in self-evaluation among job seekers.Overall,women’s self-evaluations show a more positive attitude than those of men,extending the research on gender perspectives in the workplace and contributing to further studies on the changing personality traits and gender concepts of contemporary workers.展开更多
For air-to-air missiles, the terminal guidance’s preci-sion is directly contingent upon the tracking capabilities of the roll-pitch seeker. This paper presents a combined non-singular fast terminal sliding mode contr...For air-to-air missiles, the terminal guidance’s preci-sion is directly contingent upon the tracking capabilities of the roll-pitch seeker. This paper presents a combined non-singular fast terminal sliding mode control method, aimed at resolving the frame control problem of roll-pitch seeker tracking high maneu-vering target. The sliding mode surface is structured around the principle of segmentation, which enables the control system’s rapid attainment of the zero point and ensure global fast conver-gence. The system’s state is more swiftly converged to the slid-ing mode surface through an improved adaptive fast dual power reaching law. Utilizing an extended state observer, the overall disturbance is both identified and compensated. The validation of the system’s stability and its convergence within a finite-time is grounded in Lyapunov’s stability criteria. The performance of the introduced control method is confirmed through roll-pitch seeker tracking control simulation. Data analysis reveals that newly proposed control technique significantly outperforms existing sliding mode control methods by rapidly converging the frame to the target angle, reduce the tracking error of the detec-tor for the target, and bolster tracking precision of the roll-pitch seeker huring disturbed conditions.展开更多
A composite target seeker gyro with dual spectral range infrared rays and millimeter waves, and the associated control methodology are developed. The static pressure air floated ball bearing is used to sustain the ou...A composite target seeker gyro with dual spectral range infrared rays and millimeter waves, and the associated control methodology are developed. The static pressure air floated ball bearing is used to sustain the outer frame, the optical fiber and wave guide are used to transmit these two kinds of signals to the rear part of the gyro, and the stator coils are used to get non contact angular measurement. Composite guiding, scanning, tracing and controlling can be achieved, the maximum tracing angular velocity can be as high as 16(°)/s.展开更多
AIM: To provide a comprehensive overview of clinical studies on the clinical picture of Internet-use related addictions from a holistic perspective. A literature search was conducted using the database Web of Science....AIM: To provide a comprehensive overview of clinical studies on the clinical picture of Internet-use related addictions from a holistic perspective. A literature search was conducted using the database Web of Science.METHODS: Over the last 15 years, the number of Internet users has increased by 1000%, and at the same time, research on addictive Internet use has proliferated. Internet addiction has not yet been understood very well, and research on its etiology and natural history is still in its infancy. In 2013, the American Psychiatric Association included Internet Gaming Disorder in the appendix of the updated version of the Diagnostic and Statistical Manual for Mental Disorders(DSM-5) as condition that requires further research prior to official inclusion in the main manual, with important repercussions for research and treatment. To date, reviews have focused on clinical and treatment studies of Internet addiction and Internet Gaming Disorder. This arguably limits the analysis to a specific diagnosis of a potential disorder that has not yet been officially recognised in the Western world, rather than a comprehensive and inclusive investigation of Internet-use related addictions(including problematic Internet use) more generally. RESULTS: The systematic literature review identified a total of 46 relevant studies. The included studies used clinical samples, and focused on characteristics of treatment seekers and online addiction treatment. Four main types of clinical research studies were identified, namely research involving(1) treatment seeker characteristics;(2) psychopharmacotherapy;(3) psychological therapy; and(4) combined treatment. CONCLUSION: A consensus regarding diagnostic criteria and measures is needed to improve reliability across studies and to develop effective and efficient treatment approaches for treatment seekers.展开更多
Aim To study the effect of aerodynamically stabilized seeker dynamics on guided bomb system analysis. Methods A thorough analysis of aerodynamically stabilized seeker dynamics was made to show that because of the mu...Aim To study the effect of aerodynamically stabilized seeker dynamics on guided bomb system analysis. Methods A thorough analysis of aerodynamically stabilized seeker dynamics was made to show that because of the much smaller time constant, its dynamic model can be greatly simplified. Results and Conclusion In guided bomb guidance/control digital simulation, with the use of the simplified seeker model, simulation time can be reduced without the loss of simulation accuracy.展开更多
Globalization in the Internet era has rendered job mobility and migration frequent and important social phenomena, with implications at several different levels of societies. In addition, migration, either voluntary o...Globalization in the Internet era has rendered job mobility and migration frequent and important social phenomena, with implications at several different levels of societies. In addition, migration, either voluntary or forced, is accompanied by significant changes in suicide ideation, frequency of suicide attempts and rates of suicide of people that migrate compared to the host country. However, several different peculiarities render the interpretation of the interaction of migration-suicidality as quite complex. This article provides an overview of the most significant aspects that contribute to this complexity, in order to provide the reader with a road map for better orientation in a world of rapidly changing landscapes.展开更多
Background: Human immunodeficiency virus (HIV) is a major public health concern and cause of death globally including Kenya. HIV infection is characterised by CD4+ lymphocyte depletion manifested through the loss of t...Background: Human immunodeficiency virus (HIV) is a major public health concern and cause of death globally including Kenya. HIV infection is characterised by CD4+ lymphocyte depletion manifested through the loss of the immune response capacity. Aim: This study aimed to determine the prevalence of HIV infection and CD4+T cell counts among suspected tuberculosis (TB) cases seeking healthcare at TB clinics in Mombasa County, Kenya. Study Design: Hospital and laboratory based cross-sectional study was carried between May 2011 and November 2013 in Coast General Referral Hospital, Tudor, Port-Reitz, Mlaleo, Likoni and Mikandani districts and sub-districts hospitals. Methodology: A total of 500 suspected TB cases (271 males and 229 females) were screened for HIV infection using Trinity Biotech Uni-Gold<sup>TM</sup> test and positives confirmed with the enzyme- linked immunosorbent assay. CD4+ and CD8+T cells were analyzed using a BD FACS Count flow cytometer. A questionnaire was used to collect demographic data of the participants. Results: In total, 127 (25.4%) of the suspects were HIV infected 55.1% females and 44.9% males. Females were significantly affected than males (OR = 0.78;95% CI: 0.44 - 1.37;p = 0.042). The majority (36.2%) of the HIV cases were in the 25 - 34 years age group followed by the 35 - 44 (33.9%), 45 - 54 (16.5%) and 18 - 24 (7.1%) age groups, respectively. Widowed (AOR = 6.14;95% CI: 1.53 - 20.54;p < 0.033), alcohol (AOR = 2.83;95% CI: 1.71 - 4.87;p < 0.001) and condom use (AOR = 2.31;95% CI: 1.62 = 4.71;p < 0.002) were risk factors associated with HIV infection. The mean CD4 cell count was 333.27 ± 150.59 cells/mm3 and it was higher in males (343.05 ± 149.33 cells/mm3) than females (325.93 ± 152.92 cells). The mean values of white blood cells (5.9 ± 2.42) × 109/l), packed cell value (34.1% ± 4.3%), platelets (195.16 ± 88.7) × 109/l and erythrocyte sedimentation rate (102.0 ± 17.4 mm/hr) were significantly lower than the control group (p < 0.05). Conclusion: The prevalence of HIV infection among suspected TB cases was 25.4% which was higher than the current national average HIV prevalence of 6.9%. Lower CD4+ lymphocyte count was found to be the only predicting factor for HIV. There was a significant relationship between CD4/ESR and HIV infection.展开更多
A novel heuristic search algorithm called seeker op- timization algorithm （SOA） is proposed for the real-parameter optimization. The proposed SOA is based on simulating the act of human searching. In the SOA, search...A novel heuristic search algorithm called seeker op- timization algorithm （SOA） is proposed for the real-parameter optimization. The proposed SOA is based on simulating the act of human searching. In the SOA, search direction is based on empir- ical gradients by evaluating the response to the position changes, while step length is based on uncertainty reasoning by using a simple fuzzy rule. The effectiveness of the SOA is evaluated by using a challenging set of typically complex functions in compari- son to differential evolution （DE） and three modified particle swarm optimization （PSO） algorithms. The simulation results show that the performance of the SOA is superior or comparable to that of the other algorithms.展开更多
The strap-down seeker,which combines the seeker's and the onboard gyro's measurements to obtain the target information,has been extensively applied by spinning missiles.The response delay of the strap-down see...The strap-down seeker,which combines the seeker's and the onboard gyro's measurements to obtain the target information,has been extensively applied by spinning missiles.The response delay of the strap-down seeker,a novel factor that could result in crosscoupling between the acceleration commands in the pitch and yaw channels and subsequently cause the significant deterioration in dynamic stability of the spinning missile equipped with a rate loop,is noted in this paper.The sufficient and necessary stability conditions are also analytically established based on the system equation with complex coefficient,which are further verified by numerical simulations.It could be indicated that the response delay of the strap-down seeker will greatly deteriorate the dynamic stability of the whole guidance system designed by the conventional method.It is also noticed from analysis that the stable region of the combined guidance coefficient is shrunken significantly with the increase of the spinning rate.展开更多
Conventional semi-active laser guidance takes advantage of the laser designator to illuminate the stable and uniform laser spot on target precisely.The seeker collects the reflected light by a quadrant detector and ou...Conventional semi-active laser guidance takes advantage of the laser designator to illuminate the stable and uniform laser spot on target precisely.The seeker collects the reflected light by a quadrant detector and outputs the relative position information to guide the missile to the illuminating laser spot.However,the designation and guidance accuracy could be jeopardized by the randomly drifting of laser spot caused by the instability of designation platform and air turbulence.In this work,ghost imaging technique is adapted to a quadrant detector semi-active seeker by utilizing structured illumination on the target.With a series of structured illumination masks,the signals from the quadrant detector are multiplexed to perform calculation of the target relative position as well as image reconstruction of the illuminated area simultaneously.Automatic target recognition methods could be further applied to the reconstructed image to calculate the designating error and correct the guidance.The results of simulation and experiment demonstrate that the proposed method could improve the guidance accuracy in many circumstances which would lead to attacking deviation if conventional semi-active laser guidance is used.展开更多
This article presents a novel method to measure unbalanced moments in a two-axis gimbaled seeker commonly believed to seviously influence the tracking accuracy and stabilizing capability. This method enables individua...This article presents a novel method to measure unbalanced moments in a two-axis gimbaled seeker commonly believed to seviously influence the tracking accuracy and stabilizing capability. This method enables individual measurement of unbalanced moments, and judgment of the seeker＇ s status-balanced or not. Furthermore, an instrument is designed based on this method and calibrated. The effectiveness of the proposed method is validated through a simulation. The experimental results show a satisfied level of accuracy the measurements have. This work forms a basis for the further development of a more stabilized gimbaled seeker with less induced vibration and consumed power.展开更多
The measurement of the rolling angle of the projectile is one of the key technologies for the terminal correction projectile.To improve the resolution accuracy of the rolling angle in the laser seeker weapon system, t...The measurement of the rolling angle of the projectile is one of the key technologies for the terminal correction projectile.To improve the resolution accuracy of the rolling angle in the laser seeker weapon system, the imaging model of the detector, calculation model of the position and the signal-to-noise ratio(SNR) model of the circuit are built to derive both the correlation between the resolution error of the rolling angle and the spot position, and the relation between the position resolution error and the SNR. Then the influence of each parameter on the SNR is analyzed at large,and the parameters of the circuit are determined. Meanwhile, the SNR and noise voltage of the circuit are calculated according to the SNR model and the decay model of the laser energy. Finally,the actual photoelectric detection circuit is built, whose SNR is measured to be up to 53 d B. It can fully meet the requirement of0.5° for the resolution error of the rolling angle, thereby realizing the analysis of critical technology for photoelectric detection of laser seeker signals.展开更多
Using super resolution direction of arrival（DOA） estimation algorithm to reduce the resolution angle is an effective method for passive radar seeker（PRS） to antagonize non-coherent radar decoy.Considering the powe...Using super resolution direction of arrival（DOA） estimation algorithm to reduce the resolution angle is an effective method for passive radar seeker（PRS） to antagonize non-coherent radar decoy.Considering the power and correlation property between radar and non-coherent decoy,an improved subspace DOA estimation method based on traditional subspace algorithm is proposed.Because this new method uses the invariance property of noise subspace,compared with traditional MUSIC algorithm,it shows not only better resolution in condition of closely spaced sources,but also superior performance in case of different power or partially correlated sources.Using this new method,PRS can distinguish radar and non-coherent decoy with good performance.Both the simulation result and the experimental data confirm the performance of the method.展开更多
Background:The German Military Medical Service contributed to the medical screening of unaccompanied minor refugees(UMRs)coming to Germany in 2014 and 2015.In this study,a broad range of diagnostic procedures was appl...Background:The German Military Medical Service contributed to the medical screening of unaccompanied minor refugees(UMRs)coming to Germany in 2014 and 2015.In this study,a broad range of diagnostic procedures was applied to identify microorganisms with clinical or public health significance.Previously,those tests had only been used to screen soldiers returning from tropical deployments.This instance is the first time the approach has been studied in a humanitarian context.Methods:The offered screenings included blood cell counts,hepatitis B serology and microscopy of the stool to look for protozoa and worm eggs as well as PCR from stool samples targeting pathogenic bacteria,protozoa and helminths.If individuals refused certain assessments,their decision to do so was accepted.A total of 219 apparently healthy male UMRs coming from Afghanistan,Egypt,Somalia,Eritrea,Syria,Ghana,Guinea,Iran,Algeria,Iraq,Benin,Gambia,Libya,Morocco,Pakistan,and Palestine were assessed.All UMRs who were examined at the study department were included in the assessment.Results:We detected decreasing frequencies of pathogens that included diarrhoea-associated bacteria[Campylobacter(C.)jejuni,enteropathogenic Escherichia(E.)coli(EPEC),enterotoxic E.coli(ETEC),enteroaggregative E.coli(EAEC),enteroinvasive E.coli(EIEC)/Shigella spp.),Giardia(G.)duodenalis,helminths(comprising Schistosoma spp.,Hymenolepis(H.)nana,Strongyloides(S.)stercoralis]as well as hepatitis B virus.Pathogenic microorganisms dominated the samples by far.While G.duodenalis was detected in 11.4%of the assessed UMRs,the incidence of newly identified cases in the German population was 4.5 cases per 100,000 inhabitants.Conclusion:We conclude that the applied in-house PCR screening systems,which have proven to be useful for screening military returnees from tropical deployments,can also be used for health assessment of immigrants from the respective sites.Apparently healthy UMRs may be enterically colonized with a broad variety of pathogenic and apathogenic microorganisms.Increased colonization rates,as shown for G.duodenalis,can pose a hygiene problem in centralized homes for asylum seekers.展开更多
Aiming at intercepting large maneuvering targets precisely,the guidance law of advanced self-seeking missiles requires not only inertial line-of-sight(LOS)angular rate but also target maneuvering acceleration.Moreover...Aiming at intercepting large maneuvering targets precisely,the guidance law of advanced self-seeking missiles requires not only inertial line-of-sight(LOS)angular rate but also target maneuvering acceleration.Moreover,the semi-strapdown stabilization platform has lost the ability to measure the inertial LOS angular rate directly,which needs to be extracted by numerical calculation.The differential operation commonly used in traditional methods can magnify the measurement error of the sensor,resulting in insufficient calculation accuracy of the line-of-sight angular rate.By analyzing the mathematical relationship between the missile-target relative motion and the angle tracking system,a multi-process-fusion integrated filter model of relative motion and angle tracking is presented.To overcome the defect that the infrared seeker cannot directly measure the missile-target distance,following the snake-hot-eye visual mechanism,a visual bionic imaging guidance method of estimating the missile-target relative distance from the infrared images is proposed to improve the observability of the filter model.Finally,target-tracking simulations verify that the estimation accuracy of target acceleration is improved by four times.展开更多
This paper focuses on the influence of the disturbance rejection rate(DRR)and parasitic loop parameters on the stability domain of the roll-pitch seeker's guidance system.The DRR models of the roll-pitch seeker ca...This paper focuses on the influence of the disturbance rejection rate(DRR)and parasitic loop parameters on the stability domain of the roll-pitch seeker's guidance system.The DRR models of the roll-pitch seeker caused by different types of disturbance torques and the scale deviation of different sensors are established.The optimal DRR model of the roll-pitch seeker,which contains the scale deviation model,is proposed by formula derivation.The model of the roll-pitch seeker's guidance system is established and equivalently simplified by the dimensionless method.The Lyapunov stability criterion for stability analysis of the guidance system is given by means of the passivity theorem and related definitions and lemmas.A simplified model of the roll-pitch seeker's guidance system,which is suitable for the Lyapunov stability criterion,is established by formula derivation and equivalent transformation.Three conditions that satisfy the Lyapunov stability criterion are obtained.Mathematical simulation with Nyquist plots is used to analyze the influence of different DRR parameters on the stability domain of the roll-pitch seeker's guidance system.Simulation results of this paper can provide reference for the stability analysis of systems related to the roll-pitch seeker.展开更多
文摘Attitude pursuit guidance law is suitable for low cost missiles.A strap-down seeker is used to achieve this guidance law.The additional angles of attack or sideslip caused by wind and by control system are considered as two disturbing factors which make attitude pursuit law impossible.Therefore,general attitude pursuit guidance law did not account for this two disturbing factors,because with those disturbing factors,it is difficult to apply.To solve the problem,the principle of strap-down seeker detecting target is investigated,the mathematical control model is established,then a modified attitude pursuit guidance law which employs the angular correction for those two disturbing factors is presented.It is proved that the modified attitude pursuit guidance law is appropriated to both in the presence of the additional angle of attack or sideslip via the simulations with the mathematical control model and Monte-Carlo method.
文摘Social gender theory emphasizes that gender is a cultural construct,and thus self-evaluations in the job application process inevitably differ between men and women.This study analyzes the online resumes of job seekers from several technologybased companies in Chengdu,Sichuan Province,and finds the following:1.Compared to men,women are more likely to highlight their learning ability,positive personality,sense of responsibility,communication skills,teamwork ability,adaptability,and past experiences or certifications in their self-evaluations.2.In contrast,men are more likely than women to emphasize their hardworking attitude in their self-evaluations.3.There are no significant gender differences in the presentation of self-assessment on stress resistance and execution ability.This study highlights gender differences in self-evaluation among job seekers.Overall,women’s self-evaluations show a more positive attitude than those of men,extending the research on gender perspectives in the workplace and contributing to further studies on the changing personality traits and gender concepts of contemporary workers.
文摘For air-to-air missiles, the terminal guidance’s preci-sion is directly contingent upon the tracking capabilities of the roll-pitch seeker. This paper presents a combined non-singular fast terminal sliding mode control method, aimed at resolving the frame control problem of roll-pitch seeker tracking high maneu-vering target. The sliding mode surface is structured around the principle of segmentation, which enables the control system’s rapid attainment of the zero point and ensure global fast conver-gence. The system’s state is more swiftly converged to the slid-ing mode surface through an improved adaptive fast dual power reaching law. Utilizing an extended state observer, the overall disturbance is both identified and compensated. The validation of the system’s stability and its convergence within a finite-time is grounded in Lyapunov’s stability criteria. The performance of the introduced control method is confirmed through roll-pitch seeker tracking control simulation. Data analysis reveals that newly proposed control technique significantly outperforms existing sliding mode control methods by rapidly converging the frame to the target angle, reduce the tracking error of the detec-tor for the target, and bolster tracking precision of the roll-pitch seeker huring disturbed conditions.
文摘A composite target seeker gyro with dual spectral range infrared rays and millimeter waves, and the associated control methodology are developed. The static pressure air floated ball bearing is used to sustain the outer frame, the optical fiber and wave guide are used to transmit these two kinds of signals to the rear part of the gyro, and the stator coils are used to get non contact angular measurement. Composite guiding, scanning, tracing and controlling can be achieved, the maximum tracing angular velocity can be as high as 16(°)/s.
基金Supported by A grant from the European Commission("Tech Use Disorders"Grant ID:FP7-PEOPLE-2013-IEF-627999)awarded to Olatz Lopez-Fernandez
文摘AIM: To provide a comprehensive overview of clinical studies on the clinical picture of Internet-use related addictions from a holistic perspective. A literature search was conducted using the database Web of Science.METHODS: Over the last 15 years, the number of Internet users has increased by 1000%, and at the same time, research on addictive Internet use has proliferated. Internet addiction has not yet been understood very well, and research on its etiology and natural history is still in its infancy. In 2013, the American Psychiatric Association included Internet Gaming Disorder in the appendix of the updated version of the Diagnostic and Statistical Manual for Mental Disorders(DSM-5) as condition that requires further research prior to official inclusion in the main manual, with important repercussions for research and treatment. To date, reviews have focused on clinical and treatment studies of Internet addiction and Internet Gaming Disorder. This arguably limits the analysis to a specific diagnosis of a potential disorder that has not yet been officially recognised in the Western world, rather than a comprehensive and inclusive investigation of Internet-use related addictions(including problematic Internet use) more generally. RESULTS: The systematic literature review identified a total of 46 relevant studies. The included studies used clinical samples, and focused on characteristics of treatment seekers and online addiction treatment. Four main types of clinical research studies were identified, namely research involving(1) treatment seeker characteristics;(2) psychopharmacotherapy;(3) psychological therapy; and(4) combined treatment. CONCLUSION: A consensus regarding diagnostic criteria and measures is needed to improve reliability across studies and to develop effective and efficient treatment approaches for treatment seekers.
文摘Aim To study the effect of aerodynamically stabilized seeker dynamics on guided bomb system analysis. Methods A thorough analysis of aerodynamically stabilized seeker dynamics was made to show that because of the much smaller time constant, its dynamic model can be greatly simplified. Results and Conclusion In guided bomb guidance/control digital simulation, with the use of the simplified seeker model, simulation time can be reduced without the loss of simulation accuracy.
文摘Globalization in the Internet era has rendered job mobility and migration frequent and important social phenomena, with implications at several different levels of societies. In addition, migration, either voluntary or forced, is accompanied by significant changes in suicide ideation, frequency of suicide attempts and rates of suicide of people that migrate compared to the host country. However, several different peculiarities render the interpretation of the interaction of migration-suicidality as quite complex. This article provides an overview of the most significant aspects that contribute to this complexity, in order to provide the reader with a road map for better orientation in a world of rapidly changing landscapes.
文摘Background: Human immunodeficiency virus (HIV) is a major public health concern and cause of death globally including Kenya. HIV infection is characterised by CD4+ lymphocyte depletion manifested through the loss of the immune response capacity. Aim: This study aimed to determine the prevalence of HIV infection and CD4+T cell counts among suspected tuberculosis (TB) cases seeking healthcare at TB clinics in Mombasa County, Kenya. Study Design: Hospital and laboratory based cross-sectional study was carried between May 2011 and November 2013 in Coast General Referral Hospital, Tudor, Port-Reitz, Mlaleo, Likoni and Mikandani districts and sub-districts hospitals. Methodology: A total of 500 suspected TB cases (271 males and 229 females) were screened for HIV infection using Trinity Biotech Uni-Gold<sup>TM</sup> test and positives confirmed with the enzyme- linked immunosorbent assay. CD4+ and CD8+T cells were analyzed using a BD FACS Count flow cytometer. A questionnaire was used to collect demographic data of the participants. Results: In total, 127 (25.4%) of the suspects were HIV infected 55.1% females and 44.9% males. Females were significantly affected than males (OR = 0.78;95% CI: 0.44 - 1.37;p = 0.042). The majority (36.2%) of the HIV cases were in the 25 - 34 years age group followed by the 35 - 44 (33.9%), 45 - 54 (16.5%) and 18 - 24 (7.1%) age groups, respectively. Widowed (AOR = 6.14;95% CI: 1.53 - 20.54;p < 0.033), alcohol (AOR = 2.83;95% CI: 1.71 - 4.87;p < 0.001) and condom use (AOR = 2.31;95% CI: 1.62 = 4.71;p < 0.002) were risk factors associated with HIV infection. The mean CD4 cell count was 333.27 ± 150.59 cells/mm3 and it was higher in males (343.05 ± 149.33 cells/mm3) than females (325.93 ± 152.92 cells). The mean values of white blood cells (5.9 ± 2.42) × 109/l), packed cell value (34.1% ± 4.3%), platelets (195.16 ± 88.7) × 109/l and erythrocyte sedimentation rate (102.0 ± 17.4 mm/hr) were significantly lower than the control group (p < 0.05). Conclusion: The prevalence of HIV infection among suspected TB cases was 25.4% which was higher than the current national average HIV prevalence of 6.9%. Lower CD4+ lymphocyte count was found to be the only predicting factor for HIV. There was a significant relationship between CD4/ESR and HIV infection.
基金supported by the National Natural Science Foundation of China(60870004)
文摘A novel heuristic search algorithm called seeker op- timization algorithm （SOA） is proposed for the real-parameter optimization. The proposed SOA is based on simulating the act of human searching. In the SOA, search direction is based on empir- ical gradients by evaluating the response to the position changes, while step length is based on uncertainty reasoning by using a simple fuzzy rule. The effectiveness of the SOA is evaluated by using a challenging set of typically complex functions in compari- son to differential evolution （DE） and three modified particle swarm optimization （PSO） algorithms. The simulation results show that the performance of the SOA is superior or comparable to that of the other algorithms.
基金the financial support from National Science Foundation of China(No.11532002)。
文摘The strap-down seeker,which combines the seeker's and the onboard gyro's measurements to obtain the target information,has been extensively applied by spinning missiles.The response delay of the strap-down seeker,a novel factor that could result in crosscoupling between the acceleration commands in the pitch and yaw channels and subsequently cause the significant deterioration in dynamic stability of the spinning missile equipped with a rate loop,is noted in this paper.The sufficient and necessary stability conditions are also analytically established based on the system equation with complex coefficient,which are further verified by numerical simulations.It could be indicated that the response delay of the strap-down seeker will greatly deteriorate the dynamic stability of the whole guidance system designed by the conventional method.It is also noticed from analysis that the stable region of the combined guidance coefficient is shrunken significantly with the increase of the spinning rate.
基金co-supported by National Natural Science Foundation of China(Nos.61922011 and 61675016)the Fundamental Research Funds for the Central Universities。
文摘Conventional semi-active laser guidance takes advantage of the laser designator to illuminate the stable and uniform laser spot on target precisely.The seeker collects the reflected light by a quadrant detector and outputs the relative position information to guide the missile to the illuminating laser spot.However,the designation and guidance accuracy could be jeopardized by the randomly drifting of laser spot caused by the instability of designation platform and air turbulence.In this work,ghost imaging technique is adapted to a quadrant detector semi-active seeker by utilizing structured illumination on the target.With a series of structured illumination masks,the signals from the quadrant detector are multiplexed to perform calculation of the target relative position as well as image reconstruction of the illuminated area simultaneously.Automatic target recognition methods could be further applied to the reconstructed image to calculate the designating error and correct the guidance.The results of simulation and experiment demonstrate that the proposed method could improve the guidance accuracy in many circumstances which would lead to attacking deviation if conventional semi-active laser guidance is used.
文摘This article presents a novel method to measure unbalanced moments in a two-axis gimbaled seeker commonly believed to seviously influence the tracking accuracy and stabilizing capability. This method enables individual measurement of unbalanced moments, and judgment of the seeker＇ s status-balanced or not. Furthermore, an instrument is designed based on this method and calibrated. The effectiveness of the proposed method is validated through a simulation. The experimental results show a satisfied level of accuracy the measurements have. This work forms a basis for the further development of a more stabilized gimbaled seeker with less induced vibration and consumed power.
基金supported by the National Natural Science Foundation of China(61201391)
文摘The measurement of the rolling angle of the projectile is one of the key technologies for the terminal correction projectile.To improve the resolution accuracy of the rolling angle in the laser seeker weapon system, the imaging model of the detector, calculation model of the position and the signal-to-noise ratio(SNR) model of the circuit are built to derive both the correlation between the resolution error of the rolling angle and the spot position, and the relation between the position resolution error and the SNR. Then the influence of each parameter on the SNR is analyzed at large,and the parameters of the circuit are determined. Meanwhile, the SNR and noise voltage of the circuit are calculated according to the SNR model and the decay model of the laser energy. Finally,the actual photoelectric detection circuit is built, whose SNR is measured to be up to 53 d B. It can fully meet the requirement of0.5° for the resolution error of the rolling angle, thereby realizing the analysis of critical technology for photoelectric detection of laser seeker signals.
文摘Using super resolution direction of arrival（DOA） estimation algorithm to reduce the resolution angle is an effective method for passive radar seeker（PRS） to antagonize non-coherent radar decoy.Considering the power and correlation property between radar and non-coherent decoy,an improved subspace DOA estimation method based on traditional subspace algorithm is proposed.Because this new method uses the invariance property of noise subspace,compared with traditional MUSIC algorithm,it shows not only better resolution in condition of closely spaced sources,but also superior performance in case of different power or partially correlated sources.Using this new method,PRS can distinguish radar and non-coherent decoy with good performance.Both the simulation result and the experimental data confirm the performance of the method.
文摘Background:The German Military Medical Service contributed to the medical screening of unaccompanied minor refugees(UMRs)coming to Germany in 2014 and 2015.In this study,a broad range of diagnostic procedures was applied to identify microorganisms with clinical or public health significance.Previously,those tests had only been used to screen soldiers returning from tropical deployments.This instance is the first time the approach has been studied in a humanitarian context.Methods:The offered screenings included blood cell counts,hepatitis B serology and microscopy of the stool to look for protozoa and worm eggs as well as PCR from stool samples targeting pathogenic bacteria,protozoa and helminths.If individuals refused certain assessments,their decision to do so was accepted.A total of 219 apparently healthy male UMRs coming from Afghanistan,Egypt,Somalia,Eritrea,Syria,Ghana,Guinea,Iran,Algeria,Iraq,Benin,Gambia,Libya,Morocco,Pakistan,and Palestine were assessed.All UMRs who were examined at the study department were included in the assessment.Results:We detected decreasing frequencies of pathogens that included diarrhoea-associated bacteria[Campylobacter(C.)jejuni,enteropathogenic Escherichia(E.)coli(EPEC),enterotoxic E.coli(ETEC),enteroaggregative E.coli(EAEC),enteroinvasive E.coli(EIEC)/Shigella spp.),Giardia(G.)duodenalis,helminths(comprising Schistosoma spp.,Hymenolepis(H.)nana,Strongyloides(S.)stercoralis]as well as hepatitis B virus.Pathogenic microorganisms dominated the samples by far.While G.duodenalis was detected in 11.4%of the assessed UMRs,the incidence of newly identified cases in the German population was 4.5 cases per 100,000 inhabitants.Conclusion:We conclude that the applied in-house PCR screening systems,which have proven to be useful for screening military returnees from tropical deployments,can also be used for health assessment of immigrants from the respective sites.Apparently healthy UMRs may be enterically colonized with a broad variety of pathogenic and apathogenic microorganisms.Increased colonization rates,as shown for G.duodenalis,can pose a hygiene problem in centralized homes for asylum seekers.
基金sponsored by the National Natural Science Foundation of China under Grant No.51979275the Joint Open Research Fund Program of State Key Laboratory of Hydroscience and Engineering and Tsinghua—Ningxia Yinchuan Joint Institute of Internet of Waters on Digital Water Governance under Grant No.sklhse-2022-Iow08+2 种基金the Open Fund of Key Laboratory of Urban Land Resources Monitoring and Simulation,Ministry of Natural Resources under Grant No.KF-2021-06-115the National Key R&D Program of China under Grant No.2018YFD0700603the 2115 Talent Development Program of China Agricultural University.
文摘Aiming at intercepting large maneuvering targets precisely,the guidance law of advanced self-seeking missiles requires not only inertial line-of-sight(LOS)angular rate but also target maneuvering acceleration.Moreover,the semi-strapdown stabilization platform has lost the ability to measure the inertial LOS angular rate directly,which needs to be extracted by numerical calculation.The differential operation commonly used in traditional methods can magnify the measurement error of the sensor,resulting in insufficient calculation accuracy of the line-of-sight angular rate.By analyzing the mathematical relationship between the missile-target relative motion and the angle tracking system,a multi-process-fusion integrated filter model of relative motion and angle tracking is presented.To overcome the defect that the infrared seeker cannot directly measure the missile-target distance,following the snake-hot-eye visual mechanism,a visual bionic imaging guidance method of estimating the missile-target relative distance from the infrared images is proposed to improve the observability of the filter model.Finally,target-tracking simulations verify that the estimation accuracy of target acceleration is improved by four times.
基金supported by the Defense Science and Technology Key Laboratory Fund of Luoyang Electro-optical Equipment Institute,Aviation Industry Corporation of China(6142504200108)。
文摘This paper focuses on the influence of the disturbance rejection rate(DRR)and parasitic loop parameters on the stability domain of the roll-pitch seeker's guidance system.The DRR models of the roll-pitch seeker caused by different types of disturbance torques and the scale deviation of different sensors are established.The optimal DRR model of the roll-pitch seeker,which contains the scale deviation model,is proposed by formula derivation.The model of the roll-pitch seeker's guidance system is established and equivalently simplified by the dimensionless method.The Lyapunov stability criterion for stability analysis of the guidance system is given by means of the passivity theorem and related definitions and lemmas.A simplified model of the roll-pitch seeker's guidance system,which is suitable for the Lyapunov stability criterion,is established by formula derivation and equivalent transformation.Three conditions that satisfy the Lyapunov stability criterion are obtained.Mathematical simulation with Nyquist plots is used to analyze the influence of different DRR parameters on the stability domain of the roll-pitch seeker's guidance system.Simulation results of this paper can provide reference for the stability analysis of systems related to the roll-pitch seeker.
