Delcam授权南京阳帆软件有限公司为Delcam产品增值经销商

英国Delcam（中国）有限公司最近与南京阳帆软件有限公司正式签约，授权南京阳帆软件有限公司为Delcam系列产品在江苏、浙江等华东地区的增值经销商。

阳帆

事物的发展规律总是经历萌芽、发展、鼎盛和衰败各个阶段的。中国画也是如此,从其诞生伊始就经历着各种创新和改良,历经各个时期优秀画家的不懈努力才达到相对完备的状态。《艺术沙龙》：怎样理解中国画的传承与创新？关于时代性,你有什么看法？阳帆：关于传承与创新的话题一直以来都有各种声音,我个人认为这需要辩证地看。所谓传承即传接继承之意。既然值得传接继承.那么此＂物＂就必须要有一个身份和地位,即它必须是在其所处时代中较为优秀且对后世发展大有裨益的。但是我们会很简单地发现,有什么事物是从一开始诞生就已在其所处时代中较为优秀且对后世发展大有裨益的？事物的发展规律总是经历萌芽、发展、鼎盛和衰败各个阶段的。中国画也是如此,

直挂“阳帆”上苍穹

有一种帆船,它不是在长江、黄河上扬帆而行的风帆船,而是在宇宙中利用太阳能来开动的＂太空帆船＂,它叫做太阳帆飞船。

朋友,请你原谅我

今天,与往常一样,我和小伙伴熊雨桐、周子悦一起走在回家的路上。我和周子悦一边走,一边聊游戏。突然,熊雨桐的一句话打断了我们的热聊：＂周子悦,你身上有钱吗？我要去买‘亲嘴烧＇（一种十分便宜的食品,五毛钱就能买两包）。＂周子悦无奈地摇了摇头,说：＂对不起,我没带钱。＂说着,她将两边的裤兜一拉,里面空空如也。＂你看到了吗？我真的一分钱也没有。＂熊雨桐将目光投向了我。

最傻的人成功了

1862年,德国哥丁根大学医学院的亨尔教授迎来了他的新学生。在对新生进行面试和笔试后,亨尔教授脸上露出了笑容,但他马上又神色凝重起来。因为他隐约感觉到这届学生中的很大一部分人是他教学生涯中碰到的最聪明的苗子。开学不久的一天,亨尔教授突然把自己多年积下的论文手稿全部搬到教室里,分给学生们,让他们重新仔细工整地誊写一遍。

最傻的人成功了

1862年,德国哥丁根大学医学院的亨尔教授迎来了他的新学生。在对新生进行面试和笔试后,亨尔教授脸上露出了笑容,但他马上又神色凝重起来。因为他隐约感觉到这届学生中的很大一部分人是他教学生涯中碰到的最聪明的苗子。开学不久的一天。

Optimal control of a spacecraft with deployable solar arrays using particle swarm optimization algorithm

The optimal control problem of the multibody dynamics of a spacecraft in space, modeled as a central body with one-sided connected deployable solar arrays, is investigated. The dynamical equations of motion of the spacecraft with solar arrays are derived using the multibody dynamics method. The control of the attitude motion of a spacecraft system can be transformed into the motion planning problem of nonholonomic system when the initial angular momentum is zero. These are then used to investigate the motion planning of the spacecraft during solar arrays deployment via particle swarm optimization (PSO) and results are obtained with the optimal control input and the optimal trajectory. The results of numerical simulation show that this approach is effective for the control problem of the attitude of a spacecraft during the deployment process of its solar arrays.

Feasibility analysis of the angular momentum reversal trajectory via hodograph method for high performance solar sails

In this paper a new phase space of hodograph method is adopted to investigate and better understand the two-dimensional angular momentum reversal(H-reversal) trajectories for high performance solar sails within a fixed cone angle.As the hodograph method and the H-reversal trajectory are not very common,both of them are briefly introduced.The relationship between them are constructed and addressed with a sample trajectory.How the phase space varies according to the sail quality and the fixed sail cone angle is also studied.Through variation of the phase space,the minimum sail lightness number can be obtained by solving a set of algebraic equations instead of a parameter optimization problem.For a given sail lightness number,there are three types of the two-dimensional possible heliocentric motion,including the spiral inward trajectories towards the Sun,the H-reversal trajectories and the directly outward escape trajectories.The boundaries that separate these different groups are easily determined by using the phase space.Finally,the method and procedures to achieve the feasible region of the H-reversal trajectory with required perihelion distance are presented in detail.

Control of large angle maneuvers for the flexible solar sail

Solar sail is a new type of spacecraft for deep space exploration,which flies by the pressure of sunlight.The attitude of the sail determines its orbit,so altitude control plays an important role in the mission.However,the large flexible structure leads to some difficulty in attitude control.This paper establishes the reduced dynamic model of a flexible solar sail with foreshortening deformation,and coupling with its attitude and vibration.As usual,large angle maneuvering will lead to the vibration of flexible structure,so the time optimal control of solar sail maneuvering is considered.Bang-Bang control of the solar sail generates large amplitude and sustained vibration,while the combined control based on input shaping can eliminate the vibration efficiently.With the comparison of two reduced models,it is demonstrated that the choice of two models depends on the attention to the stretching deformation.

A new solar sail orbit

Solar sail is used to achieve a geocentric sun-synchronous frozen orbit.This kind of orbit combines the characteristics of both sun-synchronous orbits and frozen orbits.Furthermore,the impossible orbits for a typical spacecraft such as sun-synchronous orbits whose inclination is less than 90° are also possible for solar sail.To achieve a sun-synchronous frozen orbit,the characteristic acceleration of the sail is chosen properly.In addition,the attitude of the sail is adjusted to keep the sun-synchronous and frozen characteristics.The perturbations including atmosphere drag,third-body gravitational forces and shaded regions are discussed,where the atmosphere drag is cancelled by solar radiation pressure force,third-body gravitational forces have negligible effects on the orbit and the shaded region can be avoided by choosing the classical orbit elements of the sail.At last,a numerical example is employed to validate the sun-synchronous frozen characteristics of the sail.

Venus round trip using solar sail

Trajectory optimization and simulation is performed for Venus round trip (VeRT) mission using solar sail propulsion. Solar gravity is included but atmospheric drag and shadowing effects are neglected in the planet-centered escape and capture stages. The spacecraft starts from the Geostationary orbit (GEt) at a predetermined time to prepare a good initial condition for the Earth-Venus transfer, although the launch window is not an issue for spacecraft with solar sails. The Earth-Venus phase and the return trip are divided into three segments. Two methods are adopted to maintain the mission trajectory for the VeRT mis- sion and then compared through a numerical simulation. According to the first approach, Planet-centered and heliocentric ma- neuvers are modeled using a set of blended analytical control laws instead of the optimal control techniques. The second pro- cedure is the Direct Attitude Angle Optimization in which the attitude angles of the solar sail are adopted as the optimization variables during the heliocentric transfer. Although neither of the two methods guarantees a globally optimal trajectory, they are more efficient and will produce a near-optimal solution if employed properly. The second method has produced a better result for the minimum-time transfer of the VeRT mission demonstrating the effectiveness of the methods in the preliminary design of the complex optimal interplanetary orbit transfers.

Fuel consumption for interplanetary missions of solar sailing

The orbits of solar sails can be changed by adjusting the sail’s attitude through external control torques.The resulting momentum will be changed,either provided by a typical attitude control subsystem or by a propellantless device.This paper investigates the extra momentum input and fuel consumption for a typical attitude control subsystem.The minimum-time transfer trajectories are designed for two rendezvous missions using both indirect and direct methods,generating continuous and discrete attitude histories,respectively.The results show that the momentum variation is almost wholly due to the solar radiation pressure.The feasibility of using tip-mounted microthrusters for attitude control is evaluated.The results show that less than0.1 kg of propellant are required for an interplanetary transfer mission when pulsed plasma thrusters with a specific impulse of700 s and a thrust of 150 mN are mounted at the tip of a 20 m square solar sail.The fuel consumptions of two transfer missions indicate that a tip-mounted pulsed plasma thruster is a viable technique for the attitude control of a solar sail.

A curved surface solar radiation pressure force model for solar sail deformation

A precise force model is of vital importance for dynamics and control of solar sails. Among various factors, deviations from the ideal flat sails, elastic deformations of the sails, are really important as most solar sails are large flexible membranes. In this study, the deformed sails are modeled as smooth curved surfaces and a general total force model (GTFM) for the deformed sails is proposed. Various simplified versions of this GTFM are also derived for the symmetric deformation cases. Furthermore, differences between the ideal force models and our precise GTFM are investigated. The numerical results demonstrate that both the previous ideal reflected model and flat optical model are not as satisfactory as claimed before, by contrast with the actual dynamics from the GTFM. Thus this work paves the way for sail craft's precise navigation where exact forces are needed.

Solar sailing trajectory optimization with planetary gravity assist

Significant propellant mass saving can be obtained with the use of complex multiple intermediate flyby maneuvers for conventional propulsion systems,and trip time also decreases for a portion of the proper solar sail missions.This paper discusses the performance of gravity assist(GA)in the time-optimal control problem of solar sailing with respect to sail lightness number and the energy difference between the initial and final orbit in the rendezvous problem in a two-body model,in which the GA is modeled as a substantial change in the velocity of the sailcraft at the GA time.In addition,this paper presents a method to solve the time-optimal problem of solar sailing with GA in a full ephemeris model,which introduces the third body’s gravity in a dynamic equation.This study builds a set of inner constraints that can describe the GA process accurately.Finally,this study presents an example for evaluating the accuracy and rationality of the two-body model’s simplification of GA by comparison with the full ephemeris model.