Modeling and Analyzing Electromagnetic Interference Signal in Complex Battlefield Environments

Electronic jamming is the key technology of electronic countermeasure, for which models and simulations are studied on noise jamming, deception jamming, and chaff jamming. In the noise jamming, the simulation analysis of radio frequency noise jamming is conducted and the theoretical models of other forms of noise jamming are built. The simulation analysis of range-gate pull off (RGPO) is carried out in the deception jamming. In addition, theoretical modeling and simulation analysis of chaff jamming are carried out with the Monte Carlo method. Simulation results show that the models are correct and can be used to simulate the statistical characteristics of chaff jamming. With the development and wide application of electronic technology, radar, communication, navigation, and IFF signals constitute a complex electromagnetic environment. It is a must to study electronic jamming technology in the complex electromagnetic environment, which will play an indispensable role in the construction of information team and victory in the countermeasure of information technology.

Synthetic aperture radar (SAR) has been involved in military applications such as high resolution imaging, battle field surveillance, and moving target detection. Recently noise and deception jamming signal are introduced to counter SAR sensor, thus these jamming techniques can be used to protect ground targets or objects of high interest. In this paper, a comparative study of the performance of the deceptive and the noise jamming on a SAR focused image, with and without jamming, is performed. Two evaluations craterous, structural similarity index measure (SSIM), and correlation coefficient (CC) are used to measure the previous jamming techniques effect on a real SAR focused image (object of high interest). The computer based simulation results, reveal that for the same CC, the power required by the deceptive jamming is reduced by three order of magnitude compared with the power required by conventional noise jamming, mean while for the same SSIM the required power is reduced by nearly two order of magnitude.

Blanket deception jamming is characteristic of both noise jamming and deception jamming, which cause some traditional anti-jamming measures invalid such as sidelobe canceling and sidelobe blanking and so on. In this work, an approach of time-space cascade adaptive sidelobe canceling based on jamming sample recognition is presented. Even when the number of jammings is more than that of auxiliary channels, the suppression results is still very good. The computer simulations demonstrate the validity.

This paper describes the challenges of detection and parameter estimation priori unknown multi-component radar signals with linear frequency modulation (LFM) in intense noise and complex jamming conditions. A method including two stages is proposed: The first stage is to detect signals, or in other words, estimate the chirp rate, and second is to estimate the pulse width of signals. The proposed approach is firstly examined by identifying the LFM signals in the environment of intense noise and mixing that noise with the continuous wave (CW) signal in MATLAB. An experiment with real-time LFM signals confirms that the method is able to detect and estimate the parameters of multi-component LFM signals in intense noise or in combining CW signal and that noise with a signal-to-noise ratio (SNR) greater than -18dB and -12dB, respectively.

Experimental, theoretical and numerical modelling of the deterioration and failure process of sandstones subject to freeze–thaw cycles

The design of noise-free, low-pollutant combustion devices requires the understanding and the prediction of the combustion noise. The noise originates from the coupling between perturbations in the heat release rate with the oscillating gas (acoustic velocity). Prediction of combustion noise requires the transfer function (TF) that correlates the variation in the heat release rate of the ame with the perturbation (acoustic velocity). Computational costs prohibit an e??cient calculation of the TF by simulating all combustion phenomena associated with the ame dynamics. Simpli??ed theoretical models, such as the hydrodynamic models, allow a signi??cant reduction of the computation time and capture the main features of the ame front dynamics. The fundamental assumption of the hydrodynamic models is that the Bunsen ame, which is described as a thin layer ( ame front) separating the burnt from the unburnt gas, is attached at the burner rim. Within the thin layer approximation, the computation of the TF requires the ame area and, consequenctly, the time-dependent ame front position. By de??ning the ame front as the zero-level set of a distance function, the evolution of the ame front is described by a level set equation. The existent experiments and theoretic kinematic models based on the thin layer approximation (e.g., the G-equation model) provide contradictory information on the phase of the TF. Experiments suggest a low-pass ??lter behaviour of the gain of the TF and an increase of the TF's phase up to several ?? as the frequency increases. In contrast, most of the theoretical models indicate a saturation of the phase of the TF at the level of ??/2. Although the use of a convective wave model for the ow [80] leads to a better agreement between theory and experiments, the origin of the convective wave remains little understood. The discrepancies between theory and experiments most likely reside in the simpli??cations employed in the theoretical models. To understand the behaviour of the experimental TF, here we extend the theoretical models based on the G-equation approach. In the ??rst step, we extend the models by addressing ames that have an arbitrary cone angle and a burning velocity with variable direction. To carry out this ??rst extension we analyse the evolution of a Bunsen ame in a Poiseuille ow from an initially at pro??le to a stationary conical shape. The analysis leads to the correct derivation of the boundary conditions in the extended model employed for the ame evolution in a perturbed Poiseuille ow. We demonstrate that the new model proposed here improves the description of the front close to the boundary and, hence, the behaviour of the ame response to velocity perturbations. Because recent measurements [52] suggest that a better understanding of the TF's phase behaviour requires a hydrodynamic model that accounts for the moving edge of the ame, in the second step we extend the hydrodynamic model to account for non-attached ames. We model the ame front as an open curve by using two level set functions whose zero-level sets are locally normal at the edge point. The movement of the edge along the ame front is accounted for via a novel model for the edge speed. During computer simulations of the ame kinematics with the new extended model the local orthogonality of the level sets is preserved by employing a novel algorithm. The simulations demonstrate that our extended model qualitatively accounts for the ame stabilisation, the ame front and edge kinematics, and the stand-o?? distance of the ame above the burner rim.

During the rapid development of synthetic aperture radar (SAR), jamming techniques against SAR have aroused intensive study interests in the field of electronic counter measures (ECM). In this paper, we compare the jammer's transmitter power required by coherent deceptive jamming against SAR and by incoherent noise jamming against SAR. It is pointed out that, in order to yield same jamming-to-signal ratio (JSR) in SAR image domain, the ratio of the transmitter power of incoherent noise jamming to that of coherent deceptive jamming should be the average pulse compression gain (APCG), rather than, the pulse compression gain (PCG) in SAR image formation processing, which is different from the opinion of some literatures. Theoretical analyses are verified by simulation results.

The high-speed airflow generated when an ultra-high-speed elevator runs in the hoistway will cause a significant piston effect. Therefore, it is essential to study the variation law of the piston wind in the hoistway and the influence of different parameters on the piston wind in the hoistway. This paper first establishes the theoretical model of the piston wind in the hoistway when the elevator ascends, descends, and intersects based on the unsteady flow theory of the Bernoulli principle. The effectiveness and accuracy of the theoretical model are verified through experimental measurements and numerical simulations. Second, based on the verified theoretical model, the influence of the five parameters of the car speed, car height, hoistway height, blockage ratio, and frictional resistance coefficient on the variation law of the piston wind and ventilation rate in the hoistway is systematically analyzed. Integrating the five parameters, a multi-parameter universal theoretical formula for hoistway ventilation rate is proposed. Finally, a gray correlation analysis is performed on each influencing parameter, which showed that the piston wind in the elevator hoistway is most affected by the blockage ratio, followed by the car speed, hoistway height, and frictional resistance coefficient, and is least affected by the car height.

By weighing the similarity of features before and after jamming, a novel evaluation method of jamming effect on ISAR based on the similarity of features is presented in the paper. This method can reflect the impact on the target features caused by jamming, consequently, the jamming effect can be evaluated by the similarity of features. It can not only be computed easily, but also has the merit of unitary. Furthermore, Two typical noise barrage jamming modes, radio frequency (RF) noise jamming and noise frequency modulation (FM) jamming are employed in computer simulation of interference with ISAR, The results indicate the validity and feasibility of the proposed method.

In the present paper, the heat transfer process of the braking resistor is analyzed. The corresponding theoretic model is proposed and solved numerically. The standard laminar model and constant heat flux method are employed to compute the heat transfer in the parallel channels between the braking resistor strips. The numerical computations for different conditions are performed. The corresponding heat transfer relationships among the convective heat transfer coefficient, thermal boundary layer thickness, cooling air outlet temperature and braking resistor surface temperature are studied according to the computed results. Finally, the theoretical heat transfer model of flow in the braking resistor case is used to investigate the variety of the resistor temperature of the practical braking resistor applied in some type hybrid electric armored vehicle. The vehicle operating test result shows that the uncertainty of the theoretic calculation model is within 15%, which can fulfill the engineering design requirement.

Reconstruction of in vivo skin autofluorescence spectrum from microscopic properties by Monte Carlo simulation

Antibodies against 2,4,5-trichlorophenol have been prepared after theoretical and molecular modeling chemical studies of three potential immunizing haptens with the aim to find out the one mimicking best the target analyte. Competitive direct and indirect ELISAs have been developed after screening a battery of haptenized enzyme tracers and coating antigens, respectively. The relation between the degree of heterology of the competitor and the resulting immunoassay detectability has been investigated according to the electronic similarities of the competitor haptens with the target analyte taking in consideration their pK(a) values. These studies have been performed using theoretical and molecular modeling tools to find out their electronic distribution at their minimum energetic levels. The results suggest that the competitors should have a high homology to produced assays with good detectability values. On the other hand detectability improves when lowering the hapten density of the competitors. An indirect competitive ELISA has been finally selected for further investigation. The immunoassay has an IC(50) value of 0.6 microg L(-)(1) and a limit of detection of 0.084 microg L(-)(1). The selectivity of the assay is high in relation to other chlorophenols frequently present in real samples. In contrast, the brominated analogues may also be recognized with this assay.

The mechanism of shrink fit toolholder has been analyzed through theoretical modeling and finite element modeling. The performance of shrink fit toolholder mainly depends on the interference value that provides enough clamping force. Interference value between tool and shrink fit toolholder includes two separate parts named as initial interference and compensatory interference. Both types of interference and their related influencing factors are described firstly in this paper. The theoretical model for shrink fit toolholder is then developed. Finally, finite element method analysis is carried out to verify the developed theoretical model. The centrifugal force and environment temperature generated in machining process should be specially paid more attention to as the spindle rotation speed grows faster.

Introduction: the article is devoted to the study of digital platforms as a technical-technological phenomenon and the identification of their essential characteristics that have legal significance and should be included in their theoretical model formed for the further development of the legal regula-tion system. A digital platform is a multifaceted phenomenon that encompasses technical-technological, economic, social, political, biological, and, possibly, other aspects. The article examines one of these aspects, namely the technical-technological one. The paper considers digital technologies inte-grated into platforms, the use of software, computing devices, and software-hardware complexes as part of a digital platform and analyzes the architecture of its software. Based on this, legally signifi-cant provisions are formulated to be included in the theoretical model of the technical-technological aspect of digital platforms. The purpose of the study is to explore the technical-technological aspect of digital platforms, to identify the essential characteristics of this aspect that have legal significance, and ultimately to construct a theoretical model of a digital platform as a technical-technological phe-nomenon. Methods: theoretical modeling; analysis and synthesis of sources; interdisciplinary ap-proach; phenomenological analysis; formal-logical analysis; systems analysis; comparative analysis. Results: the essential characteristics of a digital platform as a technical-technological phenomenon that are included in its theoretical model have been identified; a theoretical model of the digital platform has been constructed that reflects its technical-technological nature; the legal significance of the characteristics of digital platforms included in the constructed theoretical model has been substantiated. Conclusions: the research conducted made it possible to identify common essential characteristics of the technical-technological aspect of platforms that have or may have legal significance. Based on these characteristics, a theoretical model of the digital platform as a techno-technological phenomenon has been developed. The results of this work, along with studies into other aspects of digital platforms, can serve as a foundation for forming a comprehensive theoretical model of the digital platform as a multifaceted phenomenon. Theoretical modeling of digital platforms is signifi-cant for legal research as it allows for distinguishing platforms as subjects of regulation from related phenomena and is necessary for developing a system of legal regulation in this field.

A theoretical model describing the electron transport in InAs/GaAs quantum dot infrared photodetectors, modelled as ideal quantum dot superlattices, is presented. The carrier wave functions and energy levels were evaluated using the strain dependent 8‐band k · p Hamiltonian and used to calculate all intra‐ and inter‐period transition rates due to interaction with phonons and electromagnetic radiation. The interaction with longitudinal acoustic phonons and electromagnetic radiation was treated perturbatively within the framework of Fermi's golden rule, while the interaction with longitudinal optical phonons was considered taking into account their strong coupling to electrons. The populations of energy levels were then found from a system of rate equations, and the electron current in the superlattice was subsequently extracted. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)