Objective: To study the effect of tumor infiltrating lymphocytes at cancer nest on local control of rectal cancer after preoperative radiotherapy. Methods: From Jan. 1999 to Oct. 2007, a total of 107 patients with r...Objective: To study the effect of tumor infiltrating lymphocytes at cancer nest on local control of rectal cancer after preoperative radiotherapy. Methods: From Jan. 1999 to Oct. 2007, a total of 107 patients with rectal cancer were reviewed. They were treated by preoperative radiotherapy, 30 Gy/10 fractions/12 days. Two weeks later, the patient underwent a surgical operation. Their pathological samples were kept in our hospital before and after radiotherapy. Lymphocyte infiltration (LI) degree, pathologic degradation and fibrosis degree after radiotherapy in paraffin section were evaluated under microscope. Results: After followed-up of 21 months (2-86 months), a total of 107 patients were reviewed. Univariate analysis showed that lymphocyte infiltration (LI), fibrosis and pathologic changes after radiotherapy were significant factors on local control. Logistic regression analysis showed that LI after radiotherapy was a significant effect factor on local control. Conclusion: LI, fibrosis and pathologic degradation after radiotherapy are significant for local control of rectal cancer after preoperative radiotherapy. LI after radiotherapy was a significantly prognostic index for local control of rectal cancer after preoperative radiotherapy.展开更多
Background:To protect neurological tissues,underdosing occurs in most cases of T4 nasopharyngeal carcinoma(NPC) with intracranial extension.In this study,we aimed to evaluate the effect of dosimetric inadequacy on loc...Background:To protect neurological tissues,underdosing occurs in most cases of T4 nasopharyngeal carcinoma(NPC) with intracranial extension.In this study,we aimed to evaluate the effect of dosimetric inadequacy on local control and late neurological toxicities for patients treated with intensity-modulated radiotherapy(IMRT) plus chemotherapy.Methods:We prospectively enrolled patients who had non-metastaticT4 NPC with intracranial extension treated between January 2009 and November 2013.The prescribed dose was 66.0-70.4 Gy to the primary planning target volume(primary gross tumor volume [GTVp;i.e.,the nasopharyngeal tumor] +5.0 mm).Dose-volume histogram parameters were calculated,including minimum point dose(D_(min)) and dose to 95% of the target volume(D95).All patients received chemotherapy with the cisplatin,5-fluorouracil,and docetaxel regimen.Survivals were estimated using the Kaplan-Meier method and compared using the log-rank test.Results:In total,41 patients were enrolled.The local partial response rate was 87.8% after induction chemotherapy.With a median follow-up of 51 months,7 patients experienced failure in the nasopharynx;the 3-year local failure-free survival and overall survival rates of the 41 patients were 87.4% and 90.2%,respectively.The actual mean D_(min) to the GTVp was 55.2 Gy(range 48.3-67.3 Gy),and D95 was 61.6 Gy(range 52.6-69.0 Gy).All doses received by neurological organs remained well within their dose constraints.No patients developed temporal lobe necrosis or other neurological dysfunctions.Conclusions:With relative underdosed IMRT plus effective chemotherapy,the patients achieved satisfactory local control with few late toxicities of the central nervous system.Determining the acceptable extent of dosimetric inadequacy requires further exploration.展开更多
The purpose of this study was to review the magnitude of contribution of chemotherapy(CT) in the local control of muscle invasive bladder carcinoma in the studies where a combined radio-chemotherapy(RCT) was used(how ...The purpose of this study was to review the magnitude of contribution of chemotherapy(CT) in the local control of muscle invasive bladder carcinoma in the studies where a combined radio-chemotherapy(RCT) was used(how much higher local control rates are obtained with RCT compared to RT alone).Studies on radiotherapy(RT) and combined RCT,neo-adjuvant,concurrent,adjuvant or combinations,reported after 1990 were reviewed.The mean complete response(CR) rates were significantly higher for the RCT studies compared to RT-alone studies:75.9% vs 64.4%(Wilcoxon ranksum test,P = 0.001).Eleven of the included RCT studies involved 2-3 cycles of neo-adjuvant CT,in addition to concurrent RCT.The RCT studies included the onephase type(where a full dose of RCT was given and then assessment of response and cystectomy for nonresponders followed) and the two-phase types(where an assessment of response was undertaken after an initial RCT course,followed 6 wk later by a consolidation RCT for those patients with a CR).CR rates between the two subgroups of RCT studies were 79.6%(one phase) vs 71.6%(two-phase)(P = 0.015).Theaverage achievable tumour control rates,with an acceptable rate of side effects have been around 70%,which may represent a plateau.Further increase in CR response rates demands for new chemotherapeutic agents,targeted therapies,or modified fractionation in various combinations.Quantification of RT and CT contribution to local control using radiobiological modelling in trial designs would enhance the potential for both improved outcomes and the estimation of the potential gain.展开更多
This paper is mainly about a local controller whose main function is to achieve the constant tension of the thin denier filament in the high speed winding process. A mathematic model of the induction motor while contr...This paper is mainly about a local controller whose main function is to achieve the constant tension of the thin denier filament in the high speed winding process. A mathematic model of the induction motor while controlling its stator frequency and voltage is given. A new kind of variable parameter, real time constant tension control system is presented. The paper uses the microprocessor -INTEL 8097 as the CPU of the local controller. A standard serial communication interface-RS232 is used to communicate with the main computer. Computer simulation and experiment test show that this system has good control characteristics.展开更多
Aim: To analyse and assess the effect of dose rate of 192ir-source strength on late complications and local control rate during treatment of carcinoma cervix. Materials and Methods: One hundred and two cases of carcin...Aim: To analyse and assess the effect of dose rate of 192ir-source strength on late complications and local control rate during treatment of carcinoma cervix. Materials and Methods: One hundred and two cases of carcinoma cervix were included in the study. All patients were treated with a curative intent with radical dose of radiation as per the department protocol. All patients were treated with both EBRT plus Brachytherapy with Inj. Cisplatin 40 mg/m2 weekly. Patients were divided into 2 groups based on activity i.e. group A (10-6Ci) and group B (5-2Ci). After brachytherapy, point doses were analysed based on ICRU 38 recommendations. During follow up, morbidities were evaluated using RTOG grading system. Results: There was no difference in local control and distant metastasis in both groups after six months of follow up. Late Complications were comparable in both groups irrespective of source strength. Bladder complications were minimal with no significant difference in both study groups. Further Patients were divided into four groups i.e. BED of ICRU rectal point (3 and ≥100 Gy3) and source strength (10-6Ci and 5-2Ci), when BED was >100 Gy3 resulted in higher late rectal complication rate (P 3. Conclusion: This study suggests that change in source activity did not make a difference in local control, late rectal and bladder morbidities at 6 months of follow up. Longer follow up is required to assess long term results and morbidities.展开更多
Purpose: To compare concurrent chemoradiotherapy with radiotherapy in T2N0 glottic cancer. Materials and Methods: Thirty nine patients were treated with radiotherapy alone. In detail, 30 patients treated between 1985 ...Purpose: To compare concurrent chemoradiotherapy with radiotherapy in T2N0 glottic cancer. Materials and Methods: Thirty nine patients were treated with radiotherapy alone. In detail, 30 patients treated between 1985 and 1995, and 9 patients treated between 1995 and 2010 were included in the radiotherapy alone group. Between 1995 and 2010, 22 patients were treated with concurrent chemoradiotherapy. Conventional fractionation was applied in 19 patients in the radiotherapy group and in 1 patient in the chemoradiotherapy group. Hyperfractionation was applied to 20 patients in the radiotherapy group and to 21 patients in the chemoradiotherapy group. Total dose ranged from 64 Gy to 76.8 Gy in the radiotherapy group and from 66 Gy to 76.8 Gy in the chemoradiotherapy group. Cisplatin or carboplatin was administered in the chemoradiotherapy group. Results: There were no differences in the 5-year preservation rate of vocal function (82.8% vs 87.4%, p = 0.652), local control rate (77.2% vs 92.9%, p = 0.163), and 5-year overall survival rate (86.4% vs 90.2%, p = 0.497) between the radiotherapy and chemoradiotherapy groups. Conclusion: In T2N0 glottic cancer, no difference was observed between radiotherapy alone and concurrent chemoradiotherapy groups.展开更多
A high speed LIGBT with localized lifetime control by using high dose and low en ergy helium implantation(LC-LIGBT) is proposed.Compared with conventional LIGB Ts,particle irradiation results show that trade-off relat...A high speed LIGBT with localized lifetime control by using high dose and low en ergy helium implantation(LC-LIGBT) is proposed.Compared with conventional LIGB Ts,particle irradiation results show that trade-off relationship between turn- off time and forward voltage drop is improved.At the same time,the forward volta ge drop and turn-off time of such device are researched,when localized lifetime control region place near the p+-n junction,even in p+ anode.The results s how for the first time,helium ions,which stop in the p+ anode,also contribute to the forward voltage drop increasing and turn-off time reducing.展开更多
The attitude control problem of a spacecraft underactuated by two single-gimbal control moment gyros (SGCMGs) is investigated. Small-time local controllability (STLC) of the attitude dynamics of the spacecraft-SGC...The attitude control problem of a spacecraft underactuated by two single-gimbal control moment gyros (SGCMGs) is investigated. Small-time local controllability (STLC) of the attitude dynamics of the spacecraft-SGCMGs system is analyzed via nonlinear controllability theory. The conditions that guarantee STLC of the spacecraft attitude by two non-coaxial SGCMGs are obtained with the momentum of the SGCMGs as inputs, implying that the spacecraft attitude is STLC when the total angular momentum of the whole system is zero. Moreover, our results indi- cate that under the zero-momentum restriction, full attitude stabilization is possible for a spacecraft using two non-coaxial SGCMGs. For the case of two coaxial SGCMGs, the STLC property of the spacecraft cannot be determined. In this case, an improvement to the previous full attitude stabilizing control law, which requires zero-momentum presumption, is proposed to account for the singu- larity of SGCMGs and enhance the steady state performance. Numerical simulation results demonstrate the effectiveness and advantages of the new control law.展开更多
A local control strategy is presented to switch the consensus value for the first-order multi-agent system.When the local proportional controller is employed in the multiagent systems,the Laplacian matrix of the syste...A local control strategy is presented to switch the consensus value for the first-order multi-agent system.When the local proportional controller is employed in the multiagent systems,the Laplacian matrix of the system is changed.It is proved that the changed Laplacian has the same properties as the Laplacian matrix of the original multi-agent system for the consensus.Based on this,the parameter of the local controller,which can guarantee that all the agents change the original consensus value into the desired one,is determined in terms of the matrix calculation and the stability criterion.In practice,the control system must be implemented in the discrete form.Thus,the influence of the sampling period on the stability of the discrete multi-agent system with the local controller is analysed.The simulation results show the validity of the proposed method.展开更多
A new local control spline based on shape parameters with G^2 continuity,called BLC-spline,is pro- posed.Not only is BLC-spline very smooth,but also the spline curve's characteristic polygon has only three control...A new local control spline based on shape parameters with G^2 continuity,called BLC-spline,is pro- posed.Not only is BLC-spline very smooth,but also the spline curve's characteristic polygon has only three control vertices,and the characteristic polyhedron has only nine control vertices.The behavior of lo- cal control of BLC-spline is better than that of the other splines such as cubic Bezier,B and Beta-spline.The three shape parameters β_0,β_1 and β_2 of BLC-spline,which are independent of the con- trol vertices,may be altered to change the shape of the curve or surface.It is shown that BLC-spline may be used to construct a space arc spline for DNC machining directly.That is a powerful tool for the design and manufacture of curves and surfaces in integrated CAD/CAM systems.展开更多
A flow control technique by local vibration is proposed to improve the aerodynamic performance of a typical airfoil NACA 0012. Both wind-tunnel experiments and a large eddy simulation(LES) are carried out to study the...A flow control technique by local vibration is proposed to improve the aerodynamic performance of a typical airfoil NACA 0012. Both wind-tunnel experiments and a large eddy simulation(LES) are carried out to study the effects of local vibration on drag reduction over a wide range of angles of attack. The application parameters of local vibration on the upper surface of the airfoil are first evaluated by numerical simulations.The mounted position is chosen at 0.065–0.09 of chord length from the leading edge.The influence of oscillation frequency is investigated both by numerical simulations and experiments. The optimal frequencies are near the dominant frequencies of shear layer vortices and wake vortices. The patterns of shear vortices caused by local vibration are also studied to determine the drag reduction mechanism of this flow control method. The results indicate that local vibration can improve the aerodynamic performance of the airfoil. In particular, it can reduce the drag by changing the vortex generation patterns.展开更多
Because model switching system is a typical form of Takagi-Sugeno(T-S) model which is an universal approximator of continuous nonlinear systems, we describe the model switching system as mixed logical dynamical (ML...Because model switching system is a typical form of Takagi-Sugeno(T-S) model which is an universal approximator of continuous nonlinear systems, we describe the model switching system as mixed logical dynamical (MLD) system and use it in model predictive control (MPC) in this paper. Considering that each local model is only valid in each local region,we add local constraints to local models. The stability of proposed multi-model predictive control (MMPC) algorithm is analyzed, and the performance of MMPC is also demonstrated on an inulti-multi-output(MIMO) simulated pH neutralization process.展开更多
The local control of pointed groups is generalized to the concept of relative local control,and it is proved that there exists a lifting for a covering of a block source algebra if the relative local control holds.As ...The local control of pointed groups is generalized to the concept of relative local control,and it is proved that there exists a lifting for a covering of a block source algebra if the relative local control holds.As an application,a result is proved on the source algebras of blocks,whose defect groups are direct products of a normal subgroup and a subgroup that gives a relative local control.展开更多
This article analyzes the shift factors of the descending node local time for sun-synchronous satellites and proposes a shift control method to keep the local time shift within an allowance range. It is found that the...This article analyzes the shift factors of the descending node local time for sun-synchronous satellites and proposes a shift control method to keep the local time shift within an allowance range. It is found that the satellite orbit design and the orbit injection deviation are the causes for the initial shift velocity, whereas the atmospheric drag and the sun gravitational perturbation produce the shift acceleration. To deal with these shift factors, a shift control method is put forward, through such methods as orbit variation design, orbit altitude, and inclination keeping control. The simulation experiment and practical application have proved the effectiveness of this control method.展开更多
Average size of hematite and magnetite micro and nanopowders and polydispersity index, zeta potential and distribution of particles were studied. Analysis showed that average size of the obtained particles for magneti...Average size of hematite and magnetite micro and nanopowders and polydispersity index, zeta potential and distribution of particles were studied. Analysis showed that average size of the obtained particles for magnetite is 740.9 nm, for hematite particles 30 - 35 nm. Alternate current feed source was created for hyperthermia. Proceeding from the requirements of the objectives, the U type MnZn material magneto conductors were selected, in which 10.0 and 8.0 mm width gaps were cut and glass test tubes with magnetite or hematite suspensions were placed in them. Series of experiments at various field intensity and frequencies showed that for efficient magnetic hyperthermia therapy more powerful device was needed with frequency of up to 10 Mega Hertz to achieve the temperature 43°C - 45°C necessary for full activation of Neel and Brown mechanisms in particles. At the next stage, on the basis of experimental material the anticancer mono-therapeutic effect of hyperthermia and its adjuvant action in poly chemotherapeutic treatment was presented by the use of a device created by us “Lezi”. As a result of the experiment it was shown that in all animals (outbred albino mice, 3 months old) inhibition of cancer growth was fixed and intratumoral necrosis was developed, while after 7 and 10 sessions tumors were ulcerated, which refers to positive effect of the experiment (Conclusion of Pathologicanatomical Laboratory “PATGEO”, Tbilisi, Georgia ).展开更多
The reproductive and lamb mortality data (n = 187) of the Local and crosses of Dorper × Local ewes following natural controlled breeding in Ethiopia were analysed. Data were collected during 2009-2011 at Sirinka ...The reproductive and lamb mortality data (n = 187) of the Local and crosses of Dorper × Local ewes following natural controlled breeding in Ethiopia were analysed. Data were collected during 2009-2011 at Sirinka breeding, evaluation and distribution site, eastern Amhara region of Ethiopia. Breed, lamb sex, birth season, birth year, birth type and ewes’ parity were considered as fixed effects. Data analyses were performed using general linear model procedures. Breed was a significant source of variation: the local sheep attained faster the age at first lambing than the crossbred ewe lambs (469 ± 8.45 vs. 555 ± 6.25 days, p < 0.0001), whereas the crossbred ewes weighed more than the local sheep ewes at the age of first lambing (32.7 ± 0.63 vs. 22.8 ± 0.43 kg, p < 0.0001). Birth year had also important influence on the age and weight at first lambing of ewes. Ewes showed better performance during the later study years, differences attributed due to the improved management advantages in later years. The crossbred and local ewes were comparable in their litter size, despite the fact that the lambing interval of crossbred ewes was longer than the local ewes (306 ± 4.62 vs. 287 ± 2.38 days). Additionally, there was no significant difference in mortality rate between the two breeds. This study confirms that the local ewes had higher annual reproductive rate than that of the crossbred sheep ewes (1.49 ± 0.02 vs. 1.37 ± 0.01 lambs) under the same environmental conditions. The present results suggested that better management and breeding program probably will increase the productivity of the local sheep.展开更多
In this paper, a formation control algorithm and an obstade avoidance control algorithm for mobile robots are developed based on a relative motion sensory system such as a pan/tilt camera vision system, without the ne...In this paper, a formation control algorithm and an obstade avoidance control algorithm for mobile robots are developed based on a relative motion sensory system such as a pan/tilt camera vision system, without the need for global sensing and between robots. This is achieved by employing the velocity variation, instead of actual velocities, as the control inputs. Simulation and experimental results have demonstrated the effectiveness of the proposed control methods.展开更多
文摘Objective: To study the effect of tumor infiltrating lymphocytes at cancer nest on local control of rectal cancer after preoperative radiotherapy. Methods: From Jan. 1999 to Oct. 2007, a total of 107 patients with rectal cancer were reviewed. They were treated by preoperative radiotherapy, 30 Gy/10 fractions/12 days. Two weeks later, the patient underwent a surgical operation. Their pathological samples were kept in our hospital before and after radiotherapy. Lymphocyte infiltration (LI) degree, pathologic degradation and fibrosis degree after radiotherapy in paraffin section were evaluated under microscope. Results: After followed-up of 21 months (2-86 months), a total of 107 patients were reviewed. Univariate analysis showed that lymphocyte infiltration (LI), fibrosis and pathologic changes after radiotherapy were significant factors on local control. Logistic regression analysis showed that LI after radiotherapy was a significant effect factor on local control. Conclusion: LI, fibrosis and pathologic degradation after radiotherapy are significant for local control of rectal cancer after preoperative radiotherapy. LI after radiotherapy was a significantly prognostic index for local control of rectal cancer after preoperative radiotherapy.
基金support of the Department of Radiation Oncology,Fudan University Shanghai Cancer Centersupported by Science and Technology Commission of Shanghai Municipality(14411962400)
文摘Background:To protect neurological tissues,underdosing occurs in most cases of T4 nasopharyngeal carcinoma(NPC) with intracranial extension.In this study,we aimed to evaluate the effect of dosimetric inadequacy on local control and late neurological toxicities for patients treated with intensity-modulated radiotherapy(IMRT) plus chemotherapy.Methods:We prospectively enrolled patients who had non-metastaticT4 NPC with intracranial extension treated between January 2009 and November 2013.The prescribed dose was 66.0-70.4 Gy to the primary planning target volume(primary gross tumor volume [GTVp;i.e.,the nasopharyngeal tumor] +5.0 mm).Dose-volume histogram parameters were calculated,including minimum point dose(D_(min)) and dose to 95% of the target volume(D95).All patients received chemotherapy with the cisplatin,5-fluorouracil,and docetaxel regimen.Survivals were estimated using the Kaplan-Meier method and compared using the log-rank test.Results:In total,41 patients were enrolled.The local partial response rate was 87.8% after induction chemotherapy.With a median follow-up of 51 months,7 patients experienced failure in the nasopharynx;the 3-year local failure-free survival and overall survival rates of the 41 patients were 87.4% and 90.2%,respectively.The actual mean D_(min) to the GTVp was 55.2 Gy(range 48.3-67.3 Gy),and D95 was 61.6 Gy(range 52.6-69.0 Gy).All doses received by neurological organs remained well within their dose constraints.No patients developed temporal lobe necrosis or other neurological dysfunctions.Conclusions:With relative underdosed IMRT plus effective chemotherapy,the patients achieved satisfactory local control with few late toxicities of the central nervous system.Determining the acceptable extent of dosimetric inadequacy requires further exploration.
文摘The purpose of this study was to review the magnitude of contribution of chemotherapy(CT) in the local control of muscle invasive bladder carcinoma in the studies where a combined radio-chemotherapy(RCT) was used(how much higher local control rates are obtained with RCT compared to RT alone).Studies on radiotherapy(RT) and combined RCT,neo-adjuvant,concurrent,adjuvant or combinations,reported after 1990 were reviewed.The mean complete response(CR) rates were significantly higher for the RCT studies compared to RT-alone studies:75.9% vs 64.4%(Wilcoxon ranksum test,P = 0.001).Eleven of the included RCT studies involved 2-3 cycles of neo-adjuvant CT,in addition to concurrent RCT.The RCT studies included the onephase type(where a full dose of RCT was given and then assessment of response and cystectomy for nonresponders followed) and the two-phase types(where an assessment of response was undertaken after an initial RCT course,followed 6 wk later by a consolidation RCT for those patients with a CR).CR rates between the two subgroups of RCT studies were 79.6%(one phase) vs 71.6%(two-phase)(P = 0.015).Theaverage achievable tumour control rates,with an acceptable rate of side effects have been around 70%,which may represent a plateau.Further increase in CR response rates demands for new chemotherapeutic agents,targeted therapies,or modified fractionation in various combinations.Quantification of RT and CT contribution to local control using radiobiological modelling in trial designs would enhance the potential for both improved outcomes and the estimation of the potential gain.
文摘This paper is mainly about a local controller whose main function is to achieve the constant tension of the thin denier filament in the high speed winding process. A mathematic model of the induction motor while controlling its stator frequency and voltage is given. A new kind of variable parameter, real time constant tension control system is presented. The paper uses the microprocessor -INTEL 8097 as the CPU of the local controller. A standard serial communication interface-RS232 is used to communicate with the main computer. Computer simulation and experiment test show that this system has good control characteristics.
文摘Aim: To analyse and assess the effect of dose rate of 192ir-source strength on late complications and local control rate during treatment of carcinoma cervix. Materials and Methods: One hundred and two cases of carcinoma cervix were included in the study. All patients were treated with a curative intent with radical dose of radiation as per the department protocol. All patients were treated with both EBRT plus Brachytherapy with Inj. Cisplatin 40 mg/m2 weekly. Patients were divided into 2 groups based on activity i.e. group A (10-6Ci) and group B (5-2Ci). After brachytherapy, point doses were analysed based on ICRU 38 recommendations. During follow up, morbidities were evaluated using RTOG grading system. Results: There was no difference in local control and distant metastasis in both groups after six months of follow up. Late Complications were comparable in both groups irrespective of source strength. Bladder complications were minimal with no significant difference in both study groups. Further Patients were divided into four groups i.e. BED of ICRU rectal point (3 and ≥100 Gy3) and source strength (10-6Ci and 5-2Ci), when BED was >100 Gy3 resulted in higher late rectal complication rate (P 3. Conclusion: This study suggests that change in source activity did not make a difference in local control, late rectal and bladder morbidities at 6 months of follow up. Longer follow up is required to assess long term results and morbidities.
文摘Purpose: To compare concurrent chemoradiotherapy with radiotherapy in T2N0 glottic cancer. Materials and Methods: Thirty nine patients were treated with radiotherapy alone. In detail, 30 patients treated between 1985 and 1995, and 9 patients treated between 1995 and 2010 were included in the radiotherapy alone group. Between 1995 and 2010, 22 patients were treated with concurrent chemoradiotherapy. Conventional fractionation was applied in 19 patients in the radiotherapy group and in 1 patient in the chemoradiotherapy group. Hyperfractionation was applied to 20 patients in the radiotherapy group and to 21 patients in the chemoradiotherapy group. Total dose ranged from 64 Gy to 76.8 Gy in the radiotherapy group and from 66 Gy to 76.8 Gy in the chemoradiotherapy group. Cisplatin or carboplatin was administered in the chemoradiotherapy group. Results: There were no differences in the 5-year preservation rate of vocal function (82.8% vs 87.4%, p = 0.652), local control rate (77.2% vs 92.9%, p = 0.163), and 5-year overall survival rate (86.4% vs 90.2%, p = 0.497) between the radiotherapy and chemoradiotherapy groups. Conclusion: In T2N0 glottic cancer, no difference was observed between radiotherapy alone and concurrent chemoradiotherapy groups.
文摘A high speed LIGBT with localized lifetime control by using high dose and low en ergy helium implantation(LC-LIGBT) is proposed.Compared with conventional LIGB Ts,particle irradiation results show that trade-off relationship between turn- off time and forward voltage drop is improved.At the same time,the forward volta ge drop and turn-off time of such device are researched,when localized lifetime control region place near the p+-n junction,even in p+ anode.The results s how for the first time,helium ions,which stop in the p+ anode,also contribute to the forward voltage drop increasing and turn-off time reducing.
基金supported by the National Natural Science Foundation of China (No.10902003)
文摘The attitude control problem of a spacecraft underactuated by two single-gimbal control moment gyros (SGCMGs) is investigated. Small-time local controllability (STLC) of the attitude dynamics of the spacecraft-SGCMGs system is analyzed via nonlinear controllability theory. The conditions that guarantee STLC of the spacecraft attitude by two non-coaxial SGCMGs are obtained with the momentum of the SGCMGs as inputs, implying that the spacecraft attitude is STLC when the total angular momentum of the whole system is zero. Moreover, our results indi- cate that under the zero-momentum restriction, full attitude stabilization is possible for a spacecraft using two non-coaxial SGCMGs. For the case of two coaxial SGCMGs, the STLC property of the spacecraft cannot be determined. In this case, an improvement to the previous full attitude stabilizing control law, which requires zero-momentum presumption, is proposed to account for the singu- larity of SGCMGs and enhance the steady state performance. Numerical simulation results demonstrate the effectiveness and advantages of the new control law.
基金supported by the National Natural Science Foundation of China[grant numbers 61273116,61074039]the National Natural Science Fund for Distinguished Young Scholar of China[grant number 61026016].
文摘A local control strategy is presented to switch the consensus value for the first-order multi-agent system.When the local proportional controller is employed in the multiagent systems,the Laplacian matrix of the system is changed.It is proved that the changed Laplacian has the same properties as the Laplacian matrix of the original multi-agent system for the consensus.Based on this,the parameter of the local controller,which can guarantee that all the agents change the original consensus value into the desired one,is determined in terms of the matrix calculation and the stability criterion.In practice,the control system must be implemented in the discrete form.Thus,the influence of the sampling period on the stability of the discrete multi-agent system with the local controller is analysed.The simulation results show the validity of the proposed method.
文摘A new local control spline based on shape parameters with G^2 continuity,called BLC-spline,is pro- posed.Not only is BLC-spline very smooth,but also the spline curve's characteristic polygon has only three control vertices,and the characteristic polyhedron has only nine control vertices.The behavior of lo- cal control of BLC-spline is better than that of the other splines such as cubic Bezier,B and Beta-spline.The three shape parameters β_0,β_1 and β_2 of BLC-spline,which are independent of the con- trol vertices,may be altered to change the shape of the curve or surface.It is shown that BLC-spline may be used to construct a space arc spline for DNC machining directly.That is a powerful tool for the design and manufacture of curves and surfaces in integrated CAD/CAM systems.
基金Project supported by the National Natural Science Foundation of China(No.11532011)the Fundamental Research Funds for the Central Universities(No.2017FZA4031)
文摘A flow control technique by local vibration is proposed to improve the aerodynamic performance of a typical airfoil NACA 0012. Both wind-tunnel experiments and a large eddy simulation(LES) are carried out to study the effects of local vibration on drag reduction over a wide range of angles of attack. The application parameters of local vibration on the upper surface of the airfoil are first evaluated by numerical simulations.The mounted position is chosen at 0.065–0.09 of chord length from the leading edge.The influence of oscillation frequency is investigated both by numerical simulations and experiments. The optimal frequencies are near the dominant frequencies of shear layer vortices and wake vortices. The patterns of shear vortices caused by local vibration are also studied to determine the drag reduction mechanism of this flow control method. The results indicate that local vibration can improve the aerodynamic performance of the airfoil. In particular, it can reduce the drag by changing the vortex generation patterns.
文摘Because model switching system is a typical form of Takagi-Sugeno(T-S) model which is an universal approximator of continuous nonlinear systems, we describe the model switching system as mixed logical dynamical (MLD) system and use it in model predictive control (MPC) in this paper. Considering that each local model is only valid in each local region,we add local constraints to local models. The stability of proposed multi-model predictive control (MMPC) algorithm is analyzed, and the performance of MMPC is also demonstrated on an inulti-multi-output(MIMO) simulated pH neutralization process.
基金Project supported by the National Natural Science Foundation of China.
文摘The local control of pointed groups is generalized to the concept of relative local control,and it is proved that there exists a lifting for a covering of a block source algebra if the relative local control holds.As an application,a result is proved on the source algebras of blocks,whose defect groups are direct products of a normal subgroup and a subgroup that gives a relative local control.
基金supported by the China Postdotoral Science Foundation(20060401004)
文摘This article analyzes the shift factors of the descending node local time for sun-synchronous satellites and proposes a shift control method to keep the local time shift within an allowance range. It is found that the satellite orbit design and the orbit injection deviation are the causes for the initial shift velocity, whereas the atmospheric drag and the sun gravitational perturbation produce the shift acceleration. To deal with these shift factors, a shift control method is put forward, through such methods as orbit variation design, orbit altitude, and inclination keeping control. The simulation experiment and practical application have proved the effectiveness of this control method.
文摘Average size of hematite and magnetite micro and nanopowders and polydispersity index, zeta potential and distribution of particles were studied. Analysis showed that average size of the obtained particles for magnetite is 740.9 nm, for hematite particles 30 - 35 nm. Alternate current feed source was created for hyperthermia. Proceeding from the requirements of the objectives, the U type MnZn material magneto conductors were selected, in which 10.0 and 8.0 mm width gaps were cut and glass test tubes with magnetite or hematite suspensions were placed in them. Series of experiments at various field intensity and frequencies showed that for efficient magnetic hyperthermia therapy more powerful device was needed with frequency of up to 10 Mega Hertz to achieve the temperature 43°C - 45°C necessary for full activation of Neel and Brown mechanisms in particles. At the next stage, on the basis of experimental material the anticancer mono-therapeutic effect of hyperthermia and its adjuvant action in poly chemotherapeutic treatment was presented by the use of a device created by us “Lezi”. As a result of the experiment it was shown that in all animals (outbred albino mice, 3 months old) inhibition of cancer growth was fixed and intratumoral necrosis was developed, while after 7 and 10 sessions tumors were ulcerated, which refers to positive effect of the experiment (Conclusion of Pathologicanatomical Laboratory “PATGEO”, Tbilisi, Georgia ).
文摘The reproductive and lamb mortality data (n = 187) of the Local and crosses of Dorper × Local ewes following natural controlled breeding in Ethiopia were analysed. Data were collected during 2009-2011 at Sirinka breeding, evaluation and distribution site, eastern Amhara region of Ethiopia. Breed, lamb sex, birth season, birth year, birth type and ewes’ parity were considered as fixed effects. Data analyses were performed using general linear model procedures. Breed was a significant source of variation: the local sheep attained faster the age at first lambing than the crossbred ewe lambs (469 ± 8.45 vs. 555 ± 6.25 days, p < 0.0001), whereas the crossbred ewes weighed more than the local sheep ewes at the age of first lambing (32.7 ± 0.63 vs. 22.8 ± 0.43 kg, p < 0.0001). Birth year had also important influence on the age and weight at first lambing of ewes. Ewes showed better performance during the later study years, differences attributed due to the improved management advantages in later years. The crossbred and local ewes were comparable in their litter size, despite the fact that the lambing interval of crossbred ewes was longer than the local ewes (306 ± 4.62 vs. 287 ± 2.38 days). Additionally, there was no significant difference in mortality rate between the two breeds. This study confirms that the local ewes had higher annual reproductive rate than that of the crossbred sheep ewes (1.49 ± 0.02 vs. 1.37 ± 0.01 lambs) under the same environmental conditions. The present results suggested that better management and breeding program probably will increase the productivity of the local sheep.
文摘In this paper, a formation control algorithm and an obstade avoidance control algorithm for mobile robots are developed based on a relative motion sensory system such as a pan/tilt camera vision system, without the need for global sensing and between robots. This is achieved by employing the velocity variation, instead of actual velocities, as the control inputs. Simulation and experimental results have demonstrated the effectiveness of the proposed control methods.