Search results

In this paper, an online convex optimization method for the exoatmospheric ascent trajectory of space interceptors is proposed. The purpose of this paper is to transform the original trajectory optimization problem into a sequence of convex optimization subproblems.

For convenience in calculating accuracy and efficiency, the complex nonlinear terminal orbital elements constraints are converted into several quadratic equality constraints, which can be better computed by a two-step correction method during the iteration. First, the nonconvex thrust magnitude constraint is convexified by the lossless convexification technique. Then, discretization and successive linearization are introduced to transform the original problem into a sequence of one convex optimization subproblem, considering different flight phases. Parameters of trust-region and penalty are also applied to improve the computation performance. To correct the deviation in real time, the iterative guidance method is applied before orbit injection.

Numerical experiments show that the algorithm proposed in this paper has good convergence and accuracy. The successive progress can converge in a few steps and 3–4 s of CPU time. Even under engine failure or mission change, the algorithm can yield satisfactory results.

The convex optimization method presented in this paper is expected to generate a reliable optimal trajectory rapidly in different situations and has great potential for onboard applications of space interceptors.

The originality of this paper lies in the proposed online trajectory optimization method and guidance algorithm of the space inceptors, especially for onboard applications in emergency situations.

The purpose of this paper is to develop an analytic hierarchy process (AHP) method in safety risk assessment on communication system based on satellite constellations through constructing safety risk index system.

An empirical study using the AHP was carried out to find the relative weights of those assessment criterion and sub‐objectives of subsystem. Then the risk scores of 15 sub‐objectives and four subsystems were calculated applying the AHP method according to the assessment result of experts.

According to the overall results from the estimation of experts the safety risk priority of net application is the highest and the safety risk priority of attack on physical equipment is the lowest. This explained that the possibility of a war in today's era, in which peace and development is the theme is very small, and risk prevention should focus more on the defense of network attacks from enemies.

This paper provides a positive analysis of safety risk for a communication system based on satellite constellations and gives an opinion in accordance with the assessment result.

An AHP method was applied in the security risk assessment of communications systems on satellite constellation and the estimation of facing risk situation of the satellite communication system was presented according to the opinion of experts.

Briefly reviews previous literature by the author before presenting an original 12 step system integration protocol designed to ensure the success of companies or countries in their efforts to develop and market new products. Looks at the issues from different strategic levels such as corporate, international, military and economic. Presents 31 case studies, including the success of Japan in microchips to the failure of Xerox to sell its invention of the Alto personal computer 3 years before Apple: from the success in DNA and Superconductor research to the success of Sunbeam in inventing and marketing food processors: and from the daring invention and production of atomic energy for survival to the successes of sewing machine inventor Howe in co‐operating on patents to compete in markets. Includes 306 questions and answers in order to qualify concepts introduced.

The purpose of this paper is to advance a digital technology that is intended to bring about innovations on the existing textile patterns.

The pattern is deemed as a relation function between colors and positions which can be learnt by the artificial neural network (ANN). The outputs of the ANN are used for the reconstruction of the pattern and the innovation is performed by interceptors in the input/output layer. The ANN is carried out with one input layer, one output layer and several hidden layers, and the capacity of the architecture is adjusted by the scale of hidden layers to accommodate different function relations of the patterns. The training is conducted repeatedly on a sample set extracted from the pixels of the pattern image to minimize the error, and the chromatic outputs of the architecture are replaced to their origins so as to rebuild the pattern. Then, the interceptors are installed into the input and output layers to modulate the positions and the colors, and consequently the innovations are achieved on the geometric formation and color distribution of the pattern.

It has turned out that the precision of reconstruction is concerned with network scale, training epochs and color mode of the sample set. Four primary innovative effects including stripes, twisters, sandification and overprints have been qualified in terms of interceptors.

This study introduces ANN into textile pattern generation and provides a novel way to perform digital innovation of textile patterns.

The paper starts with a brief review of the notion of ‘asymmetric warfare’ and asymmetric answers in the rhetoric of Soviet leaders. The point to be stressed is that the ‘asymmetric answer’ is always an unequal response by definition. The main idea of such a response is very clear: to eliminate the existing power imbalance at minimal expenses of the weaker side. The threats of ‘asymmetric answers’ on real or imagined international challenges and dangers have returned to the Russian president rhetoric in early 2000s. What has happened? The range of possible causes of this policy shift varies from the US foreign policy and various geopolitical issues to domestic reasons associated with the elections to come. The paper analyses the main versions. What actions are standing behind the words about the ‘asymmetric answers’ that might shape the landscape of international relations of the first half of the 21st century? The paper highlights this issue and looks onto the observed future of international relations.

This chapter addresses adaptation to dynamic, novel and uncertain military environments. These environments require a shift from a maneuver warfare paradigm to an asymmetric world where shifting alliances, questionable civilian loyalties, opaque cultures, and the requirement to maintain peace one day and combat the next makes for a particularly confusing situation. This new warfare paradigm requires adaptation to an uncertain, complex environment.

The initial section discusses a general cognitive model of visualization called RAVENS and its importance for adaptation developed specifically to address complex military environments. RAVENS posits that humans are inherently flexible decision makers and situation awareness depends on the ability of humans to create narrative visualizations that capture the overall context of complex military environments. Using the framework as a guideline, we will examine two important visualization research programs whose purpose is to allow military operators to rapidly adapt to volatile situations. The first program investigates cognitive effects such as the framing bias and their possible interactions with a variety of display concepts during a series of missile defense simulations. The experimenters presented risk as a spatial representation of uncertainty and target value that emphasized either expected population lost or expected population saved. The second program investigated the feasibility of using visualizations generated from Scheherazade (a coevolutionary algorithm) to aid MI analysts in predicting emergent tactics of terrorist groups during urban operations. Finally, we discuss the value of these approaches for providing coherent narrative understanding as called for in the RAVENS model.

The results of the November 2004 US elections suggest that the initial missile defense capabilities fielded in 2004 will be developed and expanded during the next 4 years. This process will require a significant amount of money, and therefore, the problem of optimal allocation of funds becomes relevant.

In this paper, the author presents a theoretical dynamic model for appropriation of funds for developing and deploying defensive systems and maintaining/modernizing offensive systems such as the country's security to be optimized. The offensive systems are regarded as state variables, and the defensive systems as control variables. The criterion of performance consists in the minimization of the number of incoming missiles which cannot be destroyed by the defensive systems. The optimal solutions are calculated by using the Pontryaguine principle.

One observes that depending on the impact of the development of missile defense systems on the modernization of offensive systems, different policies of fund appropriation should be considered. One also remarks that under given circumstances only one (in theory), or a couple of very close policies (in practice) may be regarded as optimal.

The relationship between the development of missile defense systems and the modernization of offensive systems (or the creation of new offensive systems) is studied by using dynamic systems theory. The optimal appropriation of financial funds is done by applying the principle of Pontryaguine.