Infrared signature studies of aerospace vehicles

Infrared (IR) emissions from aircraft are used to detect, track, and lock-on to the target. MAN Portable Air Defence Systems (MANPADS) have emerged as a major cause of aircraft and helicopter loss. Therefore, IR signature studies are important to counter this threat for survivability enhancement, and are an important aspect of stealth technology. This paper reviews contemporary developments in this discipline, with particular emphasis on IR signature prediction from aerospace vehicles. The role of atmosphere in IR signature analysis, and relation between IR signature level and target susceptibility are illustrated. Also, IR signature suppression systems and countermeasure techniques are discussed, to highlight their effectiveness and implications in terms of penalties.     

Galileo AltBOC signal multiresolution acquisition strategy

Herein, some critical aspects related to the acquisition of the future Galileo signals are discussed. In particular, the Alternative Binary Offset Carrier (AItBOC) modulation that will be used by the Galileo satellites to broadcast navigation signals on the E5 band is considered, addressing acquisition issues only partially analyzed in previous works. The implementation of an acquisition section for the AltBOC signals is not straightforward, since several different receiver architectures can be used and remarkable differences are required with respect to the conventional signal processing used in GPS receivers. The main problems that must be handled (risk of false lock, resolution of the search space, and computational burden) are outlined in the following. An innovative technique, called multiresolution acquisition and tailored to the AltBOC signals, is then proposed as an effective solution to previous problems. As demonstrated by means of simulations, this novel strategy can be successfully used in coherent dual-band AltBOC receiver architectures with a feasible implementation complexity and it leads to remarkable advantages in terms of acquisition time.     

变动市场环境下的马尔可夫决策

在原有马尔可夫决策的基础上,提出对应于不断发展的市场环境下的马尔可人决策的改进模型。该模型考虑市场增长对处于竞争之中的同类型公司的最终市场占有率所具有重要的影响,并给出了市场按照不同类型增长曲线发展的相应模型及最终均衡状态的含义。     

Global ena Image Simulations

The energetic neutral atom (ENA) images obtained by the ISEE and POLAR satellites pointed the way toward global imaging of the magnetospheric plasmas. The Imager for Magnetopause to Aurora Global Exploration (IMAGE) is the first mission to dedicate multiple neutral atom imagers: HENA, MENA and LENA, to monitor the ion distributions in high-, medium- and low-energy ranges, respectively. Since the start of science operation, HENA, MENA and LENA have been continuously sending down images of the ring current, ionospheric outflow, and magnetosheath enhancements from high pressure solar wind. To unfold multiple-dimensional (equal or greater than 3) plasma distributions from 2-dimensional images is not a trivial task. Comparison with simulated ENA images from a modeled ion distribution provides an important basis for interpretation of features in the observed images. Another approach is to develop image inversion methods to extract ion information from ENA images. Simulation studies have successfully reproduced and explained energetic ion drift dynamics, the transition from open to closed drift paths, and the magnetosheath response to extreme solar wind conditions. On the other hand, HENA has observed storm-time ion enhancement on the nightside toward dawn that differs from simple concepts but can be explained using more sophisticated models. LENA images from perigee passes reveal unexpected characteristics that now can be interpreted as evidence for a transient superthermal exospheric component that is gravitationally-influenced if not bound. In this paper, we will report ENA simulations performed during several IMAGE observed events. These simulations provide insight and explanations to the ENA features that were not readily understandable previously.     

CWLFM Radar for Ship Detection and Identification

Continuous wave lineal frequency modulated (CWLFM) radar presents some interesting advantages for coast surveillance and control as well as low probability of interception (LPI). This paper presents real results obtained with a radar prototype and processed with ISAR techniques. Also, results of an automatic ship identification system applied to simulated ISAR images are exposed. Moreover, radar behavior with unfavorable meteorological conditions is discussed     

Optimization of the ship's navigation and controlling system with results of sea trials

This paper considers the state-of-the-art information technologies applied to solve the automatic track-keeping problem of the ship on a preset system of straight tacks and on a preset route to the area of hydrographic survey. A navigation-and-controlling system aboard a hydrographic vessel GS-439 was used to provide the fulfillment of the task. The results of the sea trials of control problems are given. They have shown rather good accuracy of the ship track-keeping on a preset system of straight tacks and on a preset route as well as the efficiency of automatic ship passing to the first tack and passing over to the next tacks in surveying the seabed relief, using a multi-channel echo sounder     

Comments on "The GYROLITE: A New Generation Synchronous Satellite"

The effectiveness of the GYROLITE attitude stabilization is discussed on the basis of the basic mathematical equations in [1], and an avenue towards improved performance is indicated.