A novel multi-layer planar antenna array to achieve multi-polarized radiation is developed. U-shaped coupling slots are embedded in the ground plane to extend the bandwidth. The phase relation between adjacent element...A novel multi-layer planar antenna array to achieve multi-polarized radiation is developed. U-shaped coupling slots are embedded in the ground plane to extend the bandwidth. The phase relation between adjacent elements in the radiation field is analyzed when adjacent elements are fed in opposite phase. Return loss and radiation pattern are measured for a 16-element antenna array at 12.5 GHz. The radiation pattern shows a good agreement with the calculated one in the shape of the main beam. The return-loss of the proposed antenna array is less than -20 dB in the 12.5 GHz frequency band (12.25-12.75 GHz). Because of two feed ports the antenna can transmit arbitrary elliptic polarized waves if the two feed ports have different amplitude and phase. The main factors such as element spacing, substrate medium and manufacturing imperfection are analyzed and the corresponding conclusions are presented.展开更多
The development of 3D structural composites with electromagnetic(EM)wave absorption could attenuate EM waves.Herein,magnetized flower-like Cu_(9)S_(5)/ZnFe_(2)O_(4)composites were fabricated through a multistep hydrot...The development of 3D structural composites with electromagnetic(EM)wave absorption could attenuate EM waves.Herein,magnetized flower-like Cu_(9)S_(5)/ZnFe_(2)O_(4)composites were fabricated through a multistep hydrothermal method.The crystallographic and surface phase chemical information,morphological structure,and magnetic and EM parameters of the composites were analyzed.The prepared Cu_(9)S_(5)/ZnFe_(2)O_(4)composites have multiple loss paths for EM waves and present an overall 3D flower-like structure.The Cu_(9)S_(5)/ZnFe_(2)O_(4)composites exhibit a minimum reflection loss of-54.38 dB and a broad effective absorption bandwidth of 5.92 GHz.Through magnetization,ZnFe_(2)O_(4)particles are self-assembled and grown on the surfaces of Cu_(9)S_(5).Such a modification is conducive to the generation of additional cross-linking contact sites and the effective introduction of a large number of phase interfaces,crystalline defects,special three-dimensional flower-like structures,and magneto-electrical coupling loss effects.Moreover,the synergistic effect of multiple loss strategies effectively improves EM wave absorption by the material.This work can provide a strategy for the use of magnetizationmodified sulfide composite functional materials in EM wave absorption.展开更多
The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition (MPT) and the relationship between greenhouse gas and climate change. The region near ...The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition (MPT) and the relationship between greenhouse gas and climate change. The region near Dome A in Antarctica satisfies the conditions for obtaining million-years-old ice since it has low temperatures and low accumulation rates. We analyze the corresponding relation between radar wave features and the crystal orientation fabric (COF) types based on the results of multi-polarization plane radio echo sounding (RES). The results show that, even in the summit of the ice sheet, the COF type is not perfect, but is an elongated single-pole COF. Principal-axis-orientation differences of the COF among the different periods exist and reveal that the ice flow orientations are not constant but deviate clockwise with the increasing depth. This may be related to the adjacent basal valley or both height and position changes of the summit during the glacial-interglacial periods.展开更多
With the tides propagating from the open sea to the lagoon, the mean water level (MWL) in the inlet and lagoon becomes different from that at the open sea, and a setup/setdown is generated. The change of MWL (setup...With the tides propagating from the open sea to the lagoon, the mean water level (MWL) in the inlet and lagoon becomes different from that at the open sea, and a setup/setdown is generated. The change of MWL (setup/setdown) in the system imposes a great impact on regulating the development of tidal marshes, on determining the long-term water level for harbor maintenance, on the planning for the water front development with the flood control for the possible inundation, and on the interpretation of the historical sea level change when using tidal marsh peat deposits in the lagoon as the indicator for open sea' s sea level. In this case study on the mechanisms which control the setup/setdown in Xincun Inlet, Hainan in China, the 2-D barotropic mode of Eulerian - Lagrangian CIRCulation (ELCIRC) model was utilized. After model calibration and verification, a series of numerical experiments were conducted to examine the effects of bottom friction and advection terms, wetting and drying of intertidal areas, bathymetry and boundary conditions on the setup/setdown in the system. The modeling results show that setup occurs over the inlet and lagoon areas with an order of one tenth of the tide range at the entrance. The larger the bottom friction is, a larger setup is generated. Without the advection term, the setup is reduced clue to a decrease of water level gradient to compensate for the disappearance of the advection term. Even without overtides, a setup can still be developed in the system. Sea level rise and dredging in the inlet and tidal channel can cause a decrease of setup in the system, whereas shoaling of the system can increase the setup. The uniqueness of the Xincun Inlet with respect to MWL change is that there is no evident setdown in the inlet, which can be attributed to the complex geometry and bathymetry associated with the inlet system.展开更多
Complex factors including steep slopes, intense wave breaking, large bottom friction and remarkable wave setup should be considered while studying wave propagation over coral reefs, and how to simulate wave propagatio...Complex factors including steep slopes, intense wave breaking, large bottom friction and remarkable wave setup should be considered while studying wave propagation over coral reefs, and how to simulate wave propagation and setup on coral reefs efficiently has become a primary focus. Several wave models can be used on coral reefs as have been published, but further testing and comparison of the reliability and applicability of these models are needed. A comparative study of four numerical wave models (i.e., FUNWAVE-TVD, Coulwave, NHWAVE and ZZL18) is carried out in this paper. These models’ governing equations and numerical methods are compared and analyzed firstly to obtain their differences and connections;then the simulation effects of the four wave models are tested in four representative laboratory experiments. The results show that all four models can reasonably predict the spectrum transformation. Coulwave, NHWAVE and ZZL18 can predict the wave height variation more accurately;Coulwave and FUNWAVE-TVD tend to underestimate wave setup on the reef top induced by spilling breaker, while NHWAVE and ZZL18 can predict wave setup relatively accurately for all types of breakers;NHWAVE and ZZL18 can predict wave reflection by steep reef slope more accurately. This study can provide evidence for choosing suitable models for practical engineering or establishing new models.展开更多
Objective: We aim to quantify the magnitude of setup errors in intensity-modulated radiotherapy (IMRT) treated Head and Neck cancer patients and recommend appropriate PTV margin. Methods: 60 patients with head and nec...Objective: We aim to quantify the magnitude of setup errors in intensity-modulated radiotherapy (IMRT) treated Head and Neck cancer patients and recommend appropriate PTV margin. Methods: 60 patients with head and neck cancer required bilateral neck irradiation were planned and treated by simultaneous integrated boost IMRT technique either treated radically or postoperative. Patients undergoing image-guided radiotherapy (IGRT) each with once weekly scheduled cone beam computed tomography (CBCT). The 3D displacements, systematic and random errors were calculated. The appropriate PTV expansion was determined using Van Herk’s formula. Results: Mean 3D displacement was 0.16 cm in the vertical direction, 0.14 cm in the horizontal direction and 0.16 cm in the longitudinal direction. Conclusion: Use of weekly CBCT allows the planning target volume (PTV) expansion to be reduced according to our setup. The appropriate clinical target volume (CTV)-PTV margin for our institute is 0.30 cm, 0.38 cm, and 0.33 cm in the horizontal, vertical, and longitudinal directions, respectively.展开更多
A novel setup of saturated absorption spectroscopy (SAS) is presented.It is based on laser reflections at surfaces of a sample vapor cell.It only needs one cell and one photodiode and is more compact than conventional...A novel setup of saturated absorption spectroscopy (SAS) is presented.It is based on laser reflections at surfaces of a sample vapor cell.It only needs one cell and one photodiode and is more compact than conventional setups of SAS.Its spectrum is similar to a conventional SAS.The frequency stabilization performance of an external-cavity diode laser with this setup is investigated.A frequency stability of 1.1 × 10^(-11) is achieved at an averaging time of 60s in the Allen variance measurements.展开更多
This paper studies a single machine scheduling problem with time-dependent learning and setup times. Time-dependent learning means that the actual processing time of a job is a function of the sum of the normal proces...This paper studies a single machine scheduling problem with time-dependent learning and setup times. Time-dependent learning means that the actual processing time of a job is a function of the sum of the normal processing times of the jobs already scheduled. The setup time of a job is proportional to the length of the already processed jobs, that is, past-sequence-dependent (psd) setup time. We show that the addressed problem remains polynomially solvable for the objectives, i.e., minimization of the total completion time and minimization of the total weighted completion time. We also show that the smallest processing time (SPT) rule provides the optimum sequence for the addressed problem.展开更多
Objective: To examine the trajectory of psychosomatic symptoms and to explore the impact of psychosomatic symptoms on setup error in patients undergoing breast cancer radiotherapy.Methods: A total of 102 patients with...Objective: To examine the trajectory of psychosomatic symptoms and to explore the impact of psychosomatic symptoms on setup error in patients undergoing breast cancer radiotherapy.Methods: A total of 102 patients with early breast cancer who received initial radiotherapy were consecutively recruited. The M.D. Anderson Symptom Inventory(MDASI) and three different anxiety scales, i.e., the Self-Rating Anxiety Scale(SAS), State-Trait Anxiety Inventory(STAI), and Anxiety Sensitivity Index(ASI), were used in this study. The radiotherapy setup errors were measured in millimetres by comparing the real-time isocratic verification film during radiotherapy with the digitally reconstructed radiograph(DRR). Patients completed the assessment at three time points: before the initial radiotherapy(T1), before the middle radiotherapy(T2), and before the last radiotherapy(T3).Results: The SAS and STAI-State scores of breast cancer patients at T1 were significantly higher than those at T2 and T3(F=24.44, P<0.001;F=30.25, P<0.001). The core symptoms of MDASI were positively correlated with anxiety severity. The setup errors of patients with high SAS scores were greater than those of patients with low anxiety levels at T1(Z=-2.01, P=0.044). We also found that higher SAS scores were associated with a higher risk of radiotherapy setup errors at T1(B=0.458, P<0.05).Conclusions: This study seeks to identify treatment-related psychosomatic symptoms and mitigate their impact on patients and treatment. Patients with early breast cancer experienced the highest level of anxiety before the initial radiotherapy, and then, anxiety levels declined. Patients with high somatic symptoms of anxiety may have a higher risk of radiotherapy setup errors.展开更多
The m-machine no-wait flowshop scheduling problem is addressed where setup times are treated as separate from processing times. The objective is to minimize total tardiness. Different dispatching rules have been inves...The m-machine no-wait flowshop scheduling problem is addressed where setup times are treated as separate from processing times. The objective is to minimize total tardiness. Different dispatching rules have been investigated and three were found to be superior. Two heuristics, a simulated annealing (SA) and a genetic algorithm (GA), have been proposed by using the best performing dispatching rule as the initial solution for SA, and the three superior dispatching rules as part of the initial population for GA. Moreover, improved versions of SA and GA are proposed using an insertion algorithm. Extensive computational experiments reveal that the improved versions of SA and GA perform about 95% better than SA and GA. The improved version of GA outperforms the improved version of SA by about 3.5%.展开更多
In many practical flowshop production environments, there is no intermediate storage space available to keep partially completed jobs between any two machines. The workflow has to be continuous, implying that the no-w...In many practical flowshop production environments, there is no intermediate storage space available to keep partially completed jobs between any two machines. The workflow has to be continuous, implying that the no-wait conditions must be abided, which is typical in steel and plastic production. We discuss the three-machine no-wait flowshop scheduling problem where the setup times are considered as separated from processing times and sequence independent. The scheduling goal is to minimize the total flowtime. An optimal property and two heuristic algorithms for this problem are proposed. Evaluated over a large number of problems, the proposed heuristics are found that they can yield good solutions effectively with low computational complexity, and have more obvious advantage for the large size problem compared with the existing one.展开更多
An improved algorithm for multi-polarization reconstruction from compact polarimetry (CP) is proposed. According to two fundamental assumptions in compact polarimetric reconstruction, two improvements are proposed. ...An improved algorithm for multi-polarization reconstruction from compact polarimetry (CP) is proposed. According to two fundamental assumptions in compact polarimetric reconstruction, two improvements are proposed. Firstly, the four-component model-based decomposition algorithm is modified with a new volume scattering model. The decomposed helix scattering component is then used to deal with the non-reflection symmetry condition in compact polarimetric measurements. Using the decomposed power and considering the scattering mechanism of each component, an average relationship between copolarized and crosspolarized channels is developed over the original polarization state extrapolation model. E-SAR polarimetric data acquired over the Oberpfaffenhofen area and JPL/AIRSAR polarimetric data acquired over San Francisco are used for verification, and good reconstruction results are obtained, demonstrating the effectiveness of the proposed algorithm.展开更多
As a new ionic polymer-metal composite(IPMC) for artificial muscle,the mechanical performance parameters and the relationship between the deformation and the electrical parameters of the IPMC were studied. With the di...As a new ionic polymer-metal composite(IPMC) for artificial muscle,the mechanical performance parameters and the relationship between the deformation and the electrical parameters of the IPMC were studied. With the digital speckle correlation method,the constitutive relationship of the IPMC was confirmed. With non-contact photography measurement,a cantilever setup was designed to confirm the relationship between the deformation of the IPMC film and the applied voltage. The relationship curve of tip displacement of the IPMC cantilever setup vs the voltage was achieved. The results indicate that the IPMC is isotropic,its elastic modulus is 232 MPa and Poisson ratio is 0.163. The curve achieved from the test of the tip displacement of the IPMC cantilever setup shows that the tip displacement reaches the maximum when the stimulated voltage is 5 V. And the tip displacement descends largely when the frequency of the applied voltage is between 30 mHz and 100 mHz.展开更多
When an expanded-base pile is installed into ground, the cavity expansion associated with penetration of the enlarged pile base is followed by cavity contraction along the smaller-diameter pile shaft. In order to acco...When an expanded-base pile is installed into ground, the cavity expansion associated with penetration of the enlarged pile base is followed by cavity contraction along the smaller-diameter pile shaft. In order to account for the influence of cavity contraction on the change of bearing capacity of expanded-base pile, a theoretical calculation methodology, predicting the setup of expanded-base pile, was established by employing the cavity contraction theory to estimate the shaft resistance of expanded-base pile, and horizontal consolidation theory to predict the dissipation of excess pore pressure. Finally, the numerical solutions for the setup of expanded-base pile were obtained. The parametric study about the influence of cavity contraction on setup of expanded-base pile was carried out, while a field test was introduced. The parametric study shows that the decrements in radial pressure and the maximum pore water pressure after considering cavity contraction are increased as the expanded ratio(base diameter/shaft diameter) and rigidity index of soil are raised. The comparison between calculated and measured values shows that the calculated results of ultimate bearing capacity for expanded-base pile considering cavity contraction agree well with the measured values; however, the computations ignoring cavity contraction are 2.5-3.0 times the measured values.展开更多
文摘A novel multi-layer planar antenna array to achieve multi-polarized radiation is developed. U-shaped coupling slots are embedded in the ground plane to extend the bandwidth. The phase relation between adjacent elements in the radiation field is analyzed when adjacent elements are fed in opposite phase. Return loss and radiation pattern are measured for a 16-element antenna array at 12.5 GHz. The radiation pattern shows a good agreement with the calculated one in the shape of the main beam. The return-loss of the proposed antenna array is less than -20 dB in the 12.5 GHz frequency band (12.25-12.75 GHz). Because of two feed ports the antenna can transmit arbitrary elliptic polarized waves if the two feed ports have different amplitude and phase. The main factors such as element spacing, substrate medium and manufacturing imperfection are analyzed and the corresponding conclusions are presented.
基金This work was supported by the National Natural Science Foundation of China(No.51477002)the University Synergy Innovation Program of Anhui Province,China(No.GXXT-2019-028).
文摘The development of 3D structural composites with electromagnetic(EM)wave absorption could attenuate EM waves.Herein,magnetized flower-like Cu_(9)S_(5)/ZnFe_(2)O_(4)composites were fabricated through a multistep hydrothermal method.The crystallographic and surface phase chemical information,morphological structure,and magnetic and EM parameters of the composites were analyzed.The prepared Cu_(9)S_(5)/ZnFe_(2)O_(4)composites have multiple loss paths for EM waves and present an overall 3D flower-like structure.The Cu_(9)S_(5)/ZnFe_(2)O_(4)composites exhibit a minimum reflection loss of-54.38 dB and a broad effective absorption bandwidth of 5.92 GHz.Through magnetization,ZnFe_(2)O_(4)particles are self-assembled and grown on the surfaces of Cu_(9)S_(5).Such a modification is conducive to the generation of additional cross-linking contact sites and the effective introduction of a large number of phase interfaces,crystalline defects,special three-dimensional flower-like structures,and magneto-electrical coupling loss effects.Moreover,the synergistic effect of multiple loss strategies effectively improves EM wave absorption by the material.This work can provide a strategy for the use of magnetizationmodified sulfide composite functional materials in EM wave absorption.
基金the National Natural Science Foundation of China(Grant No.40874060)the 863 projection(Grant No.2006AA09Z152)
文摘The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition (MPT) and the relationship between greenhouse gas and climate change. The region near Dome A in Antarctica satisfies the conditions for obtaining million-years-old ice since it has low temperatures and low accumulation rates. We analyze the corresponding relation between radar wave features and the crystal orientation fabric (COF) types based on the results of multi-polarization plane radio echo sounding (RES). The results show that, even in the summit of the ice sheet, the COF type is not perfect, but is an elongated single-pole COF. Principal-axis-orientation differences of the COF among the different periods exist and reveal that the ice flow orientations are not constant but deviate clockwise with the increasing depth. This may be related to the adjacent basal valley or both height and position changes of the summit during the glacial-interglacial periods.
基金The National Natural Science Foundation of China under contract No. 40266001
文摘With the tides propagating from the open sea to the lagoon, the mean water level (MWL) in the inlet and lagoon becomes different from that at the open sea, and a setup/setdown is generated. The change of MWL (setup/setdown) in the system imposes a great impact on regulating the development of tidal marshes, on determining the long-term water level for harbor maintenance, on the planning for the water front development with the flood control for the possible inundation, and on the interpretation of the historical sea level change when using tidal marsh peat deposits in the lagoon as the indicator for open sea' s sea level. In this case study on the mechanisms which control the setup/setdown in Xincun Inlet, Hainan in China, the 2-D barotropic mode of Eulerian - Lagrangian CIRCulation (ELCIRC) model was utilized. After model calibration and verification, a series of numerical experiments were conducted to examine the effects of bottom friction and advection terms, wetting and drying of intertidal areas, bathymetry and boundary conditions on the setup/setdown in the system. The modeling results show that setup occurs over the inlet and lagoon areas with an order of one tenth of the tide range at the entrance. The larger the bottom friction is, a larger setup is generated. Without the advection term, the setup is reduced clue to a decrease of water level gradient to compensate for the disappearance of the advection term. Even without overtides, a setup can still be developed in the system. Sea level rise and dredging in the inlet and tidal channel can cause a decrease of setup in the system, whereas shoaling of the system can increase the setup. The uniqueness of the Xincun Inlet with respect to MWL change is that there is no evident setdown in the inlet, which can be attributed to the complex geometry and bathymetry associated with the inlet system.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.11572130 and 41106031)
文摘Complex factors including steep slopes, intense wave breaking, large bottom friction and remarkable wave setup should be considered while studying wave propagation over coral reefs, and how to simulate wave propagation and setup on coral reefs efficiently has become a primary focus. Several wave models can be used on coral reefs as have been published, but further testing and comparison of the reliability and applicability of these models are needed. A comparative study of four numerical wave models (i.e., FUNWAVE-TVD, Coulwave, NHWAVE and ZZL18) is carried out in this paper. These models’ governing equations and numerical methods are compared and analyzed firstly to obtain their differences and connections;then the simulation effects of the four wave models are tested in four representative laboratory experiments. The results show that all four models can reasonably predict the spectrum transformation. Coulwave, NHWAVE and ZZL18 can predict the wave height variation more accurately;Coulwave and FUNWAVE-TVD tend to underestimate wave setup on the reef top induced by spilling breaker, while NHWAVE and ZZL18 can predict wave setup relatively accurately for all types of breakers;NHWAVE and ZZL18 can predict wave reflection by steep reef slope more accurately. This study can provide evidence for choosing suitable models for practical engineering or establishing new models.
文摘Objective: We aim to quantify the magnitude of setup errors in intensity-modulated radiotherapy (IMRT) treated Head and Neck cancer patients and recommend appropriate PTV margin. Methods: 60 patients with head and neck cancer required bilateral neck irradiation were planned and treated by simultaneous integrated boost IMRT technique either treated radically or postoperative. Patients undergoing image-guided radiotherapy (IGRT) each with once weekly scheduled cone beam computed tomography (CBCT). The 3D displacements, systematic and random errors were calculated. The appropriate PTV expansion was determined using Van Herk’s formula. Results: Mean 3D displacement was 0.16 cm in the vertical direction, 0.14 cm in the horizontal direction and 0.16 cm in the longitudinal direction. Conclusion: Use of weekly CBCT allows the planning target volume (PTV) expansion to be reduced according to our setup. The appropriate clinical target volume (CTV)-PTV margin for our institute is 0.30 cm, 0.38 cm, and 0.33 cm in the horizontal, vertical, and longitudinal directions, respectively.
基金Supported by the National Basic Research Program of China under Grant No 2012CB921602the National Natural Science Foundation of China under Grant Nos 10874012 and 10974177the Program of International Science and Technology Cooperation of China under Grant No 2010DFA04690.
文摘A novel setup of saturated absorption spectroscopy (SAS) is presented.It is based on laser reflections at surfaces of a sample vapor cell.It only needs one cell and one photodiode and is more compact than conventional setups of SAS.Its spectrum is similar to a conventional SAS.The frequency stabilization performance of an external-cavity diode laser with this setup is investigated.A frequency stability of 1.1 × 10^(-11) is achieved at an averaging time of 60s in the Allen variance measurements.
文摘This paper studies a single machine scheduling problem with time-dependent learning and setup times. Time-dependent learning means that the actual processing time of a job is a function of the sum of the normal processing times of the jobs already scheduled. The setup time of a job is proportional to the length of the already processed jobs, that is, past-sequence-dependent (psd) setup time. We show that the addressed problem remains polynomially solvable for the objectives, i.e., minimization of the total completion time and minimization of the total weighted completion time. We also show that the smallest processing time (SPT) rule provides the optimum sequence for the addressed problem.
文摘Objective: To examine the trajectory of psychosomatic symptoms and to explore the impact of psychosomatic symptoms on setup error in patients undergoing breast cancer radiotherapy.Methods: A total of 102 patients with early breast cancer who received initial radiotherapy were consecutively recruited. The M.D. Anderson Symptom Inventory(MDASI) and three different anxiety scales, i.e., the Self-Rating Anxiety Scale(SAS), State-Trait Anxiety Inventory(STAI), and Anxiety Sensitivity Index(ASI), were used in this study. The radiotherapy setup errors were measured in millimetres by comparing the real-time isocratic verification film during radiotherapy with the digitally reconstructed radiograph(DRR). Patients completed the assessment at three time points: before the initial radiotherapy(T1), before the middle radiotherapy(T2), and before the last radiotherapy(T3).Results: The SAS and STAI-State scores of breast cancer patients at T1 were significantly higher than those at T2 and T3(F=24.44, P<0.001;F=30.25, P<0.001). The core symptoms of MDASI were positively correlated with anxiety severity. The setup errors of patients with high SAS scores were greater than those of patients with low anxiety levels at T1(Z=-2.01, P=0.044). We also found that higher SAS scores were associated with a higher risk of radiotherapy setup errors at T1(B=0.458, P<0.05).Conclusions: This study seeks to identify treatment-related psychosomatic symptoms and mitigate their impact on patients and treatment. Patients with early breast cancer experienced the highest level of anxiety before the initial radiotherapy, and then, anxiety levels declined. Patients with high somatic symptoms of anxiety may have a higher risk of radiotherapy setup errors.
文摘The m-machine no-wait flowshop scheduling problem is addressed where setup times are treated as separate from processing times. The objective is to minimize total tardiness. Different dispatching rules have been investigated and three were found to be superior. Two heuristics, a simulated annealing (SA) and a genetic algorithm (GA), have been proposed by using the best performing dispatching rule as the initial solution for SA, and the three superior dispatching rules as part of the initial population for GA. Moreover, improved versions of SA and GA are proposed using an insertion algorithm. Extensive computational experiments reveal that the improved versions of SA and GA perform about 95% better than SA and GA. The improved version of GA outperforms the improved version of SA by about 3.5%.
文摘In many practical flowshop production environments, there is no intermediate storage space available to keep partially completed jobs between any two machines. The workflow has to be continuous, implying that the no-wait conditions must be abided, which is typical in steel and plastic production. We discuss the three-machine no-wait flowshop scheduling problem where the setup times are considered as separated from processing times and sequence independent. The scheduling goal is to minimize the total flowtime. An optimal property and two heuristic algorithms for this problem are proposed. Evaluated over a large number of problems, the proposed heuristics are found that they can yield good solutions effectively with low computational complexity, and have more obvious advantage for the large size problem compared with the existing one.
基金supported by the National Natural Science Foundation of China(41171317)the State Key Program of the Natural Science Foundation of China(61132008)the Research Foundation of Tsinghua University
文摘An improved algorithm for multi-polarization reconstruction from compact polarimetry (CP) is proposed. According to two fundamental assumptions in compact polarimetric reconstruction, two improvements are proposed. Firstly, the four-component model-based decomposition algorithm is modified with a new volume scattering model. The decomposed helix scattering component is then used to deal with the non-reflection symmetry condition in compact polarimetric measurements. Using the decomposed power and considering the scattering mechanism of each component, an average relationship between copolarized and crosspolarized channels is developed over the original polarization state extrapolation model. E-SAR polarimetric data acquired over the Oberpfaffenhofen area and JPL/AIRSAR polarimetric data acquired over San Francisco are used for verification, and good reconstruction results are obtained, demonstrating the effectiveness of the proposed algorithm.
基金Project(50575228) supported by the National Natural Science Foundation of ChinaProject(07JJ3089) supported by the Hunan Provincial Natural Science Foundation of China
文摘As a new ionic polymer-metal composite(IPMC) for artificial muscle,the mechanical performance parameters and the relationship between the deformation and the electrical parameters of the IPMC were studied. With the digital speckle correlation method,the constitutive relationship of the IPMC was confirmed. With non-contact photography measurement,a cantilever setup was designed to confirm the relationship between the deformation of the IPMC film and the applied voltage. The relationship curve of tip displacement of the IPMC cantilever setup vs the voltage was achieved. The results indicate that the IPMC is isotropic,its elastic modulus is 232 MPa and Poisson ratio is 0.163. The curve achieved from the test of the tip displacement of the IPMC cantilever setup shows that the tip displacement reaches the maximum when the stimulated voltage is 5 V. And the tip displacement descends largely when the frequency of the applied voltage is between 30 mHz and 100 mHz.
基金Project(LQ15E080002)supported by Zhejiang Provincial Natural Science Foundation of ChinaProjects(5150828251478228)supported by the National Natural Science Foundation of China
文摘When an expanded-base pile is installed into ground, the cavity expansion associated with penetration of the enlarged pile base is followed by cavity contraction along the smaller-diameter pile shaft. In order to account for the influence of cavity contraction on the change of bearing capacity of expanded-base pile, a theoretical calculation methodology, predicting the setup of expanded-base pile, was established by employing the cavity contraction theory to estimate the shaft resistance of expanded-base pile, and horizontal consolidation theory to predict the dissipation of excess pore pressure. Finally, the numerical solutions for the setup of expanded-base pile were obtained. The parametric study about the influence of cavity contraction on setup of expanded-base pile was carried out, while a field test was introduced. The parametric study shows that the decrements in radial pressure and the maximum pore water pressure after considering cavity contraction are increased as the expanded ratio(base diameter/shaft diameter) and rigidity index of soil are raised. The comparison between calculated and measured values shows that the calculated results of ultimate bearing capacity for expanded-base pile considering cavity contraction agree well with the measured values; however, the computations ignoring cavity contraction are 2.5-3.0 times the measured values.