拟双曲度量空间中广义反演函数的性质

基于一般度量空间中flattening函数和admission反演函数的概念,在拟双曲度量空间中引入拟对偶的概念,并借助于拟双曲度量作为工具,结合flattening函数和admission反演函数的性质来刻画了拟双曲度量空间中广义反演函数的几何特征。

Assessment of Monitor Units and Gamma Pass Rate for 6 MV and Flattening Filter Free (FFF) Beams in Volumetric Modulated Arc Therapy (VMAT)

Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy practice now frequently uses fluence and aperture modifying techniques, such as volumetric modulated arc therapy. In these circumstances, the flattening filter in the beam manufacturing process is no longer required. It is therefore necessary to compare the monitor units of 6 MV and flattening filter free plans and how it influences the gamma pass rates to determine which is best for treating cervical cancer with pelvic lymph node metastasis. Methods: VMAT plans for fifteen patients with cervical cancer with pathological pelvic lymph node metastasis were included in this study. Each patient had two VMAT plans using conventional 6 MV beam with flattening filter and one with flattening filter free beam (FFF). The VMAT plans were made using two arcs, and then recalculated to give the planned dose distribution to the detectors in a Delta4 phantom. The VMAT plans were irradiated on the Delta4 phantom using an Elekta linear accelerator (6 MV). Results: The mean monitor unit for the 6 MV plans was 506.3 MU and a standard deviation of 48.6 while that of the FFF plans had a mean MU of 701.5 with a standard deviation of 87.6. The total monitor units (MUs) for the FFF plans were significantly greater than the 6 MV plans (p = 6.1 × 10-5). Conclusion: Flattening filter free (FFF) plans require more numbers of monitor units in comparison to conventional 6 MV filtered beams for external radiation of cervical cancer with pelvic lymph nodes involvement.

A Model of Modified Newtonian Gravity Alternative to MOND, Consistent with the Properties of Spiral Galaxies and Compatible with Extragalactic Dark Matter

A new model of the modified Newtonian gravity called Compacted & Collapsing Gravity (CCG) is proposed. Similar to the Milgrom’s MOND, it allows explaining the flattening of rotation curve in spiral galaxies, thus eliminates the need for dark matter at this level. However, in contrast to MOND, it puts a distinct limit on effective gravity;thereby constraints the sizes of single galaxies in connection to their masses, which complies with observations. In the bigger than single galaxies structures such as galaxy clusters, CCG rather complements than replaces interpretations of the observational data based on dark matter. Besides, the new model provides a plausible explanation to the hierarchical structure of the universe.

支持向量机回归模型中目标函数的五个理解

支持向量机回归和支持向量机分类有区别,分类问题主要从最大化两类间的间隔入手,而回归问题则需要寻找适合这批数据的自变量和因变量之间关系的回归方程,使得由回归方程计算出来的因变量值和实际数据中的因变量值尽量接近。并且,支持向量机回归和普通的回归问题还不一样,设定了一个2ε间隔带,在这个间隔带内的数据点、不计算损失,之外的计算损失,在尽量最小化损失的同时,模型的目标函数里多了个1/2‖W‖2,关于这个项,有很多疑问,给支持向量机回归目标函数的理解造成了很大的困难,尤其是在学习了支持向量机分类问题后,更容易把这个项和分类问题中同样的项意味着的最大化间隔相联系,但又不能直接对应上。于是,我们从正则化、结构风险最小化(岭回归、权重衰减)、回归超平面的flatten、二分类问题的转化、回归问题的本质这五个方面着手,从不同的角度进行透彻分析和解释1/2‖W‖2,从而为支持向量机回归模型的目标函数的理解进一步理清思路、扫清障碍。而且,第五个理解站在了新的高度,从问题的本质出发,统一了前面四个理解,也具有自己独特的看法。

Innovation in the Computing System of Straightening Force

Currently in China, the computing system of the straightening force of the six-rollers straightening machine generally follows the traditional computing system. The force status of the traditional computing system for the straightening force deviates far away from the actual force status of the roller system in the six-rollers straightening machine. In the traditional system, the computing model of the straightening force of the six-roller straightening machine was based on the roller shape of hyperbola, which led to the length of the contacting line between the tube and the straightening roller to be excessively short, i.e., only 0.1~）.2 of the length of the roller. Thus the constructed computing system has relatively large difference from the actual measured result. To solve the above problems, flattening straightening and bend straightening are analyzed on the basis of materials mechanics and bend beam theory, the roll er shape using the envelope method of A.I4.~e：mKoB is generated, and a new computing system for straightening force in six-rollers straightening machine is built. The roller shape of the straightening roller, on which the new computing system for the straightening force is based, is designed according to the envelope method under the condition of ideally full contacting between the tube and the roller body of the straightening roller, therefore the new computing model accords with the practical status of straightening force. According to the comparison of the new computing system with finite element method and the actual measured result of straightening force, it has been proved that the computation accuracy of the new computing system for straightening force satisfies the practical requirements of engineering. New six-rollers straightening machines are designed and manufactured according to the new calculation system, and the new machines not only have higher precision and quality, but also have adopted the force sensor and computer and combined with the new computing system for straightening force to realize the fully automatic adjustment of the straightening machine. The new six rollers straightening machine have obtained notable economical and social benefits.

Analysis of Collapse in Flattening a Micro-grooved Heat Pipe by Lateral Compression

The collapse of thin-walled micro-grooved heat pipes is a common phenomenon in the tube flattening process, which seriously influences the heat transfer performance and appearance of heat pipe. At present, there is no other better method to solve this problem. A new method by heating the heat pipe is proposed to eliminate the collapse during the flattening process. The effectiveness of the proposed method is investigated through a theoretical model, a finite element（FE） analysis, and experimental method. Firstly, A theoretical model based on a deformation model of six plastic hinges and the Antoine equation of the working fluid is established to analyze the collapse of thin walls at different temperatures. Then, the FE simulation and experiments of flattening process at different temperatures are carried out and compared with theoretical model. Finally, the FE model is followed to study the loads of the plates at different temperatures and heights of flattened heat pipes. The results of the theoretical model conform to those of the FE simulation and experiments in the flattened zone. The collapse occurs at room temperature. As the temperature increases, the collapse decreases and finally disappears at approximately 130 ℃ for various heights of flattened heat pipes. The loads of the moving plate increase as the temperature increases. Thus, the reasonable temperature for eliminating the collapse and reducing the load is approximately 130℃. The advantage of the proposed method is that the collapse is reduced or eliminated by means of the thermal deformation characteristic of heat pipe itself instead of by external support. As a result, the heat transfer efficiency of heat pipe is raised.

Fabrication of Crack-Free Flattened Bamboo and Its Macro-/MicroMorphological and Mechanical Properties

This work aimed to help the bamboo industry develop methodology for producing imperfection-free bamboo boards that can serve either decorative or structural benefit to consumers seeking to engage with the bioeconomy.Specifically,softened and slotted bamboo tubes were handled by a roller device with nails to render crack-free flattened bamboo board.Softening temperature and time were optimized herein according to findings regarding chemical composition and board mechanical properties.The optimal softening parameters for saturated steam heat treatment is proved to be 160°C for 8 min.The flattened bamboo board possesses an increased bending strength of 101.5 MPa and a decreased bending modulus of 7.7 GPa,being compared with only-softened bamboo.The corresponding changing mechanism is determined in-depth by the micro-morphological and mechanical results based on in-situ SEM and AFM technologies.Under the action of nails and rolling processes,the bamboo texture becomes compact with crushed and fragmented conduit walls.The resulting cell cavity then becomes stretched and compressed,taking on a morphology which allows for the mechanical penalties associated with flattening to be avoided.According to the micro-mechanical results obtained by AFM,compared with unflatten bamboo,the Young’s modulus of the cell membrane in transverse direction(YT)decreases to 1.00 GPa while the corresponding Young’s modulus in radial direction(YR)increases to 7.29 GPa.

Gauge-meter model building based on the effect of elastic deformation of rolls in a plate mill

The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working roll radius, backup roll radius, working roll crown, backup roll crown, and rolling force. The influence rules are hard to get by measuring. Taking a conventional 4-h plate mill as the research subject, these influences were transferred into the calculation of roll deflection and flattening deformation. To calculate these deformations, the theory of the influence function method was adopted. By modifying the traditional gauge-meter model, a novel model of the effect of roll elastic deformation on the gap setting was built by data fitting. By this model, it was convenient to analyze the variation caused by the rolling condition. Combining the elastic deformation model of rolls with the kiss-rolls method, a gauge-meter model was put forward for plate thickness prediction. The prediction precision of thickness was greatly improved by the new gauge- meter model.

Radio Frequency Induction Plasma Spraying of Molybdenum

Radio frequency (RF) induction plasma was used to make free-standing deposition of molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were investigated. The effect of process parameters such as plasma power, chamber pressure, and spray distance on the phenomena mentioned above was studied. Scanning electron microscopy (SEM) was used to analyze the plasma-processed powder, splats formed, and deposits obtained. Experimental results show that less Mo particles are spheroidized when compared to the number of spheroidized tungsten (W) particles at the same powder feed rate under the same plasma spray condition. Molten Mo particles can be sufficiently flattened on substrate. The influence of the process parameters on the flattening behavior is not significant. Mo deposit is not as dense as W deposit, due to the splash and low impact of molten Mo particles. Oxidation of the Mo powder with a large particle size is not evident under the low pressure plasma spray.

Effects of particle density on depositing properties of WC-17Co by HVOF process

The in-flight and deposition properties of three types of WC-17 Co powder with different particle densities during a high-velocity oxygen fuel （HVOF） thermal spray process were investigated. Three types of powder exhibited similar velocity upon impact on the substrate surface. The powder with the lower particle density exhibited a higher temperature upon impingement process, resulting in the generation of a higher flattening ratio. Thus, the coating derived from the powder with the lower particle density possessed superior micro-hardness, porosity and surface roughness. However, the coating with the lowest particle density showed the poorest fracture toughness because of the generation of the largest amount of amorphous phase.

Removing paint from a metal substrate using a flattened top laser

In this paper,we investigate laser cleaning using a flattened top laser to remove paint coating from a metal substrate.Under the irradiation of a flattened top laser,the coating paint of the metal substrate can be removed efficiently by laser induced ablation,stress,and displacement force.The temperature distribution,stress,and displacement are calculated in the coating layer and substrate using finite element analysis.The effects of a Gaussian laser and a flattened top laser and the results of different diameters of laser spot are compared.The investigation shows that the flattened top laser can reduce the substrate damage and enhance the cleaning efficiency.This method meets the need of large area industrial cleaning applications by optimizing the flattened top laser parameters.

Commissioning of TrueBeamTM Medical Linear Accelerator: Quantitative and Qualitative Dosimetric Analysis and Comparison of Flattening Filter (FF) and Flattening Filter Free (FFF) Beam

Motive of the study is to present quantitative and qualitative analysis and comparison of beam data measurement with FF (flattening filter) and FFF (flattening filter free) beam in a Varian TrueBeamTM Medical Linear Accelerator. Critique of beam characterization and evolution of dosimetric properties for 6 MV, 10 MV, 15 MV FF beam and 6 MVFFF, 10 MVFFF FFF beam has been carried out. We performed the comparison of photon beam data for two standard FF photon energy 6 MV, 10 MV verses 6 MVFFF, and 10 MVFFF FFF beam. Determination and comparison of parameter involved PDD (Percentage depth dose), Depth dose profile, Symmetry, Flatness, Quality index, Relative output factor, Penumbra, Transmission factor, DLG (Dosimetric leaf gap), in addition to degree of Un-flatness and off-axis ratio of FFF beam. Outcomes of presenting study had shown that change of various parameters such as Percentage depth dose curves, Shape of the depth dose profile, Transmission, Value of quality index and significant rise in surface dose for FFF in comparison with FF beam. Differences in the output factor at lower and higher field sizes for FFF beam compared to that of FF beam were found. The maximum output factor deviation between 6 MV and 6 MVFFF was found to be 4.55%, whereas in 10 MV and 10 MVFFF was 5.71%. Beam quality TPR20/10 for FFF beam was found to be lesser in magnitude, 5.42% for 6 MVFFF whereas 4.50% for 10 MVFFF compared to 6 MV and 10 MV FF beam respectively. Jaw transmission and interleaf leakage for FFF beam were found to be lesser than FF beam. Also DLG for FFF beam was found to be lesser in magnitude comparable to that of flattened beam. This study is mainly inclined towards evaluation and comparison of the FF and FFF beam. It has been observed that, the outcome of a commissioning beam data generation fully complies with vendor specification and published literature.

VARIATION OF WOVEN FABRIC GEOMETRY——Non-uniform Flattening of Yarns

In previous research much effort has been devoted to the geometry of woven fabrics and relat-ed problems under the assumption of constant yarn configuration in fabric.This paper will first re-port that image crimp (yarn crimp measured by an image analysis method) seems larger than actualvalue.From the explanation of this result,the variation of yarn configuration in woven fabric dueto the non-uniform flattening is revealed.The significance of this actual structure of woven fabricsis discussed.It is believed that the variation of yarn configuration is very important for fabric per-formance,and may be an advantage for fabric quality.

The subgenual cingulate gyrus exhibits lower rates of bifurcation in schizophrenia than in controls, bipolar disorder and depression

The subgenual cingulate cortex has been found to be different in structure and function in mood and affective disorders compared to healthy individuals. Imaging studies have shown a decrease in function of the subgenual region in bipolar disorder and depression, with overall glial number shown to be decreased in these disorders. Decreases in subgenual grey matter in SZ have been observed also. In this neuropathological study upon formalin-fixed coronal brain sections we describe the morphological finding of de- creased frequency of subgenual cingulate crown bifurcation (p = 0.02) as compared to control, bipolar and depression cases. This suggests that the cingulate cortex in schizophrenia may be morphologically distinct in utero formation, potentially enabling an early identification of high-risk individuals.

A comparative study between flattening filter-free beams and flattening filter beams in radiotherapy treatment

Flattening filter-free(FFF) beams generated by medical linear particle accelerators(linacs) have recently been used in radiotherapy clinical practice.FFF beams have fundamental physical parameter differences with respect to standard flattening filter(FF) beams,such that the generally used dosimetric parameters and definitions are not always viable.This study investigates dosimetric parameters for use in the quality assurance of FFF beams generated by medical linacs in radiotherapy.The main characteristics of the photon beams are analyzed using specific data generated by a Varian True Beam linac having both FFF and FF beams of 6 and 10 MV(megavolt) energy,respectively.Definitions for dose profile parameters are suggested,starting from the renormalization of the FFF with respect to the corresponding FF beam.From this point,the flatness concept is translated into one of "un-flatness",and other definitions are proposed,maintaining a strict parallelism between FFF and FF parameter concepts.The quality controls used in establishing a quality assurance program when introducing FFF beams into the clinical environment are given,maintaining similarity to those used for standard FF beams,and recommendations for the introduction of FFF beams into clinical radiotherapy application for breast cancer patients are provided as an example for comparison between FFF and FF for dose distribution and coverage for a target volume.Although there are many advantages of using a FFF beam,especially for advanced radiotherapy techniques,there are a few limitations(e.g.,using a relatively higher energy photon beam for stereotactic radiotherapy(SRT),limited speed of current multileaf collimators(MLCs),and off-axis distance-dependent modulation in intensitymodulated radiation therapy(IMRT)) as well as challenges(e.g.,criteria for beam quality evaluation and penumbra,establishment of dosimetry methods,and consequences of photon target burn-up) that need to be addressed for establishing the FFF beam as a viable alternative to the FF beam.

A Sensitivity Dosimetry Study of the Setup Uncertainties during Machine Commissioning and Annual QA

This study is to investigate three common potential setup uncertainties during Linac commissioning and annual QA and to evaluate how these uncertainties propagate into the quality of beam profiles and patient dosimetry using gamma analysis. Three uncertainty scenarios were purposely introduced for gantry position tilted from 0˚- 3˚(scenario 1), isocenter position misaligned from 0 - 6 mm (scenario 2) and SAD changed from 99.5 - 103 cm (scenario 3). A 60 × 60 × 60 cm3 water phantom cube was created to replicate a 3D water tank in VarianEclipse (V.11) treatment planning system (Varian Medical Systems, Palo Alto, CA). For each scenario, beam data profiles (crossline and diagonal) and PDD curves were calculated at different field sizes and depths for three energies: 6 MV, 6 MV-FFF and 10 MV-FFF. Gamma analysis method was used to compare a total of 263 profiles to baseline using a 1%/1mm parameter with 90% gamma passing rate criteria. For scenario 1, a ≥90% gamma passing rate and ≤1% dose difference were seen on both crossline and diagonal profiles, and PDD curves for gantry tilted up to 2˚. For 3˚degree tilt, the gamma passing rate decreased to ≤90% at depth of ≥20 cm for 6MV/6MV-FFF and depth of ≥12 cm for 10MV-FFF. For scenario 2, a ≤90% gamma passing rate and ≥1% dose difference were seen at depths from dmax to 20 cm for all energies. For depths ≥20 cm, mostly ≥90% gamma passing rate and ≤1% dose difference were seen. For scenario 3, a ≥90% gamma passing rate and ≤1% dose difference were seen on ≤4 mm isocenter misalignments for all energies. In summary, gamma analysis of the beam profiles is a very sensitive test for SAD deviation scenarios and can reveal issues of sub millimeter setup uncertainty. However, it is not as sensitive for isocenter misalignment scenarios. The test is also more sensitive for FFF beams than flattening filter beams.

Design of Secure Microsystems Using Current-to-Data Dependency Analysis

This paper presents a method for designing a class of countermeasures for DPA attacks based on attenuation of current variations. In this class of countermeasures, designers aim at decreasing the dynamic current variations to reduce the information that can be extracted from the current consumption of secure microsystems. The proposed method is based on a novel formula that calculates the number of current traces required for a successful DPA attack using the characteristics of the microsystem current signal and the external noise of the measurement setup. The different stages of the proposed method are illustrated through designing an example current flattening circuit. Meanwhile validity and applicability of the proposed formula is verified by comparing theoretical results with those obtained experimentally for the example circuit. The proposed formula not only estimates the required level of attenuation for a target level of robustness defined by design requirements, it also predicts the effectiveness of a countermeasure using simulation results therefore dramatically reducing the time to design of secure microsystems.

Contribution of CRUST2. 0 components to the tri-axiality of the Earth and equatorial flattening of the core

Equatorial flattening of the core were previously estimated to be 5 × 10^-4 by using seismically derived density anomaly, and 1. 7748280× 10^-5 by assuming that the ratio of polar flattening to equatorial flattening of the core is the same as that of the whole Earth. In this study, we attempted to explain the difference by applying a density-contrast stripping process to the crust in the second method. We use the CRUST2. 0 model to estimate the inertia-moment contribution resulted from the density-contrast structure in the crust to a tri-axial Earth. The contribution of the density contrast in the crust was removed layer by layer. The layers include topography, bathymetry, ice, soft sediment, hard sediment, upper crust, middle crust, lower crust and the reference crust. For the boundaries of the topography and bathymetry layers, we used ETOPO5 values with a resolution of 5＇. For boundaries of other layers, we used values from the CRUST2. 0 model with a resolution of 2~. After the contribution of density contrast is stripped, the equatorial flattening of the core was found to be 6. 544× 10 ^-5, which is still one order of magnitude smaller than the result given by the first method. This suggests that at least one of the methods is not correct. The influence of the uncertainty in the equatorial flattening of the core on the Free Core Nutation frequency is small, but its effect on the gravitational torque acting on the tri-axial inner core cannot be ignored. So an accurate determination of the equatorial flattening of the core is still necessary.

Influence of Roll Elastic Deformation on Gaugemeter Equation for Plate Rolling

The error of gaugemeter equation decreases the gap setting precision.The precision of gaugemeter equation is strongly influenced by plate width,work roll radius,backup roll radius,work roll crown,backup roll crown and rolling force.And these influences are hard to measure.All these factors are converted to roll deflection deformation and roll flattening deformation for calculation.In order to calculate the deformation,the theory of influence function method was adopted.By using simulation program,the influence of these factors on deformation was obtained.Then a simple model can be built.With this model,it is convenient to analyze the influence of different factors on gaugemeter equation.

Influence of Intersection Angle of Prefabricated Cracks on Impact Failure of Flattened Brazilian Disc

Both experimental and numerical approaches were used to study dynamic failure properties and patterns of flattened Brazilian discs,containing two prefabricated cracks intersected at a varying angle.Mechanism of crack initiation,propagation,and cut-through were scrutinized and influences of the intersection angle on specimen strength and acoustic emission performance were also studied.All primary cracks initialize near the middle or the tip points of the upper prefabricated crack,and they continue to develop along the load direction and finally cut through the specimen.The secondary cracks could be observed in directions almost horizontal or parallel to the directions of prefabricated cracks.Furthermore,it is found that stress intensity factor reaches its maximum for specimen with intersection angle of 0 degree.