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To improve their interfacial properties, 3D orthogonal woven fabrics with basalt filament yarns were modified with functionalized carboxylated carbon nanotubes (KH570-MWCNTs) and polydopamine (PDA). Fourier infrared spectroscopy (FT-IR) analysis and scanning electron microscopy (SEM) testing were used. It was demonstrated that both methods could successfully modify basalt fiber (BF) 3D woven fabrics. The 3D orthogonal woven composites (3DOWC) were produced with epoxy resin and 3D orthogonal woven fabrics as raw material by the VARTM molding process. The bending properties of the 3DOWC were tested and analyzed by experimental and finite element analysis methods. The results showed that the bending properties of the 3DOWC modified by KH570-MWCNTs and PDA were significantly improved, and the maximum bending loads were increased by 31.5% and 31.0%. The findings of the finite element simulation and the experiment results were in good agreement, and the simulation error value was 3.37%. The correctness of the finite element simulation results and the model’s validity further reveal the material’s damage situation and damage mechanism in the bending process.

Background: Oceanographic buoys generally employ satellites for positioning and data transmission. However, sea surface conditions can affect these signals. The Signal to Noise Ratio (SNR) of small observation buoys can be improved by exploiting polarization diversity. Methods: This paper discusses the effect of sea surface conditions on the polarization and reflection loss of Beidou B1 reflected signals for the purposes of exploiting polarization diversity. The Rayleigh roughness criterion is used to assess the roughness of the sea surface. The Fresnel reflection coefficients are derived to analyze the polarization and reflection loss of the Beidou B1 reflected signals with different sea surface states. Results: The results obtained show that for the Beidou B1 signals, the sea surface is considered rough for most sea surface states and incident angles. For smooth sea surfaces, the Beidou B1 reflected signals are mainly Left Hand Circularly Polarized (LHCP) waves, but Right Hand Circularly Polarized (RHCP) waves dominate when the incident angles are larger than the Brewster angle. The reflected loss is between -2 dB to -3.4 dB. In rough sea surfaces and the signals propagation is dominated by diffuse reflection. The reflection loss decreases with the incident angle and there is a fluctuation when the incident angle is around 49 degrees. The specular reflection signal has a significant amplitude when the angle of incidence is large. RHCP waves are the main component of the reflected signals, and the reflection loss is relatively small which can be employed for polarization diversity or marine remote sensing. Conclusion: polarization diversity is only useful with good sea conditions, and the corresponding gain decreases with the deterioration of the sea surface conditions.

3D woven composites offer various high-performance characteristics and wide applications due to their lightweight, high strength, and good integrity. However, to exploit their structural advantages, it is necessary to improve the interface properties between reinforcement and matrix, and carbon nanotubes with excellent mechanical properties provide a good solution to improve the interface properties of composites. Based on this motivation, the goal of this study is to investigate the impact of multiwalled carbon nanotubes on the tensile and bending properties of basalt fiber through-angle interlocking 3D woven composite, layered-angle interlocking 3D woven composite and orthogonal 3D woven composite. The obtained results indicated that the maximum warp and weft tensile loads of the layered-angle interlocking composites increased by 19.3% and 28.5% from 91,091.3N and 8,409.5N to 9,288.4N and 11,761.4N, respectively. The maximum warp and weft bending loads of 3D orthogonal composites were increased by 26.4% and 19.6% from 566.7N and 635.4N to 770.0N and 790.3N, respectively. O-MWCNTs contain -OH, -COOH and the unsaturated double bond can active functional groups and basalt fiber on the surface of the Si-OH and unsaturated double bonds in the reaction to form epoxy resin covalent bond to improve the interface between the fiber and matrix effect, which solved the key problem of interface outstanding performance of 3D woven modified-basalt fiber composites.

Background: Space-time adaptive processing (STAP) has been widely used in the fields of communication, radar, and navigation anti-jamming. However, the traditional scalar array used by STAP has certain limitations，because it can only obtain spatial information. In order to further improve the performance of the space-time domain joint filtering technology, this paper replaces the traditional scalar array with an alternating polarization sensitive array (APSA). Compared with the dual polarization sensitive array (DPSA), it can not only obtain the polarization information of the signal, but also reduce the computational complexity of the algorithm. Methods: Using the polarization information of the signals, this paper realizes an alternate polarization sensitive array space-time-polarization adaptive processing algorithm (APSA-STPAP) based on the linear variance minimum criterion (LCMV). Different from the traditional LCMV criterion, this paper takes the space-time polarization joint steering vector of the desired signal and the interference signal as the constraint matrix, and uses the "1 condition" and "zero condition" as the constraint conditions to effectively suppress the interference signal and enhance the expectation signal. Results: The simulation results show that: (1) APSA-STPAP algorithm can achieve the same filtering effect as DPSA-STPAP algorithm. From the perspective of the spatial domain, time domain and polarization domain, it can form null in the direction of interference, effectively suppress the interference signal, and realize space-time-polarization adaptive processing. (2) Under the same conditions, APSA-STPAP algorithm can achieve the same filtering effect as DPSA-STPAP algorithm. there is a big difference between the two algorithms, APSA-STPAP algorithm can effectively reduce the amount of computation. Moreover, the dipole of alternating polarization sensitive array is halved, which reduces the coupling effect between electric dipoles, and is conducive to engineering implementation. (3) APSA-STPAP algorithm can maintain good anti-interference performance even when the electric dipole and anti-jamming degree of freedom are reduced by half, and its anti-jamming performance is similar to that of polarization sensitive array. The output SINR of DPSA-STPAP algorithm is about 3dB higher than that of APSA-STPAP algorithm. There is little difference between the anti- interference performance of APSA and DPSA.

In order to solve the problem that the spatial filtering fails when the Direction of Arrival (DOA) of the desired signal and the interference signal are same or similar, first, the polarization array vector is introduced into the spatial filtering algorithm-Least Mean Square (LMS) to form the Spatial-Polarization Least Mean Square (SPLMS); then in order to overcome the contradiction between the convergence speed and steady-state error of the SPLMS, Spatial-Polarization Normalized Least Mean Square (SPLMS) is useed to improve this problem. Finally, a simulation analysis of the error curve of the SPLMS and the SPNLMS is carried out, and it is found that when the DOA of both signals are same or similar, the SPLMS can achieve a good beamforming effect. The steady-state error accuracy is obviously improved. The convergence speed is faster, stronger, and it is more superior than the SPLMS.

In order to avoid the instability of composite materials laminated tube connection between layer and layer, with green basalt fiber as raw material, through the reasonable design, the special-shaped 3D (three-dimensional) tubular woven fabrics with two different thicknesses and shapes were fabricated on a semi-automatic sample loom with low cost. The special-shaped 3D tubular woven composites were fabricated by VARTM (vacuum assisted resin transfer molding) process. Load-displacement scatter plots and fitting curves and energy-displacement scatter plots and fitting curves were obtained by lateral compression tests. The results showed that the same shape,the load and energy absorption values increased with thickness and compression property was better. For the special-shaped 3D tubular woven composites with the same thickness, the load and energy absorption values of the circular tube was larger than the square tube. The correlation coefficients of load-displacement and energy-displacement polynomial fitting formulas calculated by the least square method in the Origin 8.5 software were all close to 1, indicated that the fitting effect was good. This method provided a direction for the research of special-shaped 3D tubular woven composites.

It is challenging to acquire the first arriving path for the estimate of the time of arrival (TOA) in multipath channels, particularly for low signal to noise ratio. The energy detection (ED) receiver is a better scheme for TOA estimate in millimeter-wave (mm-Wave) ranging system since its simple circuit structure. However, the traditional algorithms for TOA estimate using ED cannot provide the adequate accuracy. In this paper, a novel ED receiver for mm-Wave TOA estimate is developed by employing the higher order cumulant technique. Results acquired in IEEE 802.15.3c models confirm the effectiveness and better performance of this solution.

Millimeter-wave (MMW) signals in 60GHz band have shown immense potential for accurate range estimation with precise time and multipath resolution. Nonline of sight (NLOS) propagation is a primary factor affecting the range precision. To improve range estimation, an Energy detector (ED) based normalized threshold algorithm which employs a Neural network (NN) is developed on the basis of NLOS identification. The maximum curl and standard deviation of the received energy block values are used to determine NLOS environment and the normalized thresholds for different Signal-to-noise ratios (SNRs). The effects of the channel and integration period are evaluated. Performance results are presented which show that the proposed approach provides better precision and is more robust than other solutions over a wide range of SNRs for the CM1.1 and CM2.1 channel models in the IEEE 802.15.3c standard.

The signal parameter estimation of polarization sensitive array mainly studies the joint estimation of DOA and polarization parameters via array sampling data. MUSIC algorithm can effectively estimate the DOA of signal source, but the resolution of MUSIC algorithm will be reduced or even invalid with low signal-to-noise ratio (SNR) and small signal interval conditions. This paper studies an improved MUSIC algorithm which can effectively estimate DOA of signal sources with low SNR and small signal interval conditions. At the same time, the joint parameter estimation based on the MUSIC algorithm is applied to uniform linear array. The simulation results show that the DOA of the signal can be clearly distinguished from the polarization domain and the spatial domain.

This research studies on vital signs (VS) like detection the motion of human respiration of via an impulse ultra-wideband (UWB) through-wall radar with a further responsive algorithm in order to remove clutter, de-noising and random-noise. betterment of the signal-to-noise ratio (SNR) of these VS signals gained utilizing one filter. Apply the wavelet packet analysis, the standard deviation based spectral kurtosis is signed up to study the signal characteristics to impart the distance calculate among the radar and alive object. The data size moderation with regard to a defined region of interest (RDI) rises the system efficiency. The frequency of respiration is estimated by a multiple time window selection algorithm. demonstrated experimental finding points to the superior efficacy and reliability of this technique. The proposed technique showed clear VS calculation than existing methods in the literature.

Underwater environment is more complex than the air and underwater acoustic signals are often hidden in the noise. Therefor, the interest signal needs to be enhanced or selected before identifying. In this paper, the signal is first enhanced by the method of beamforming, and then the acoustic signal feature is extracted and sent to softmax for recognition. The effectiveness of the method is verified by experiments.

Nowadays, contactless vital sign (VS) reorganization has been used, so get more consideration and huge realizations. The electromagnetic reorganization is observed as the most undertaking techniques, that can acquire VS in the range-frequency matrix. Ultra-wide band (UWB) impulse radar used at most of the indoor object position detecting, VS reorganization, and also human fall reorganization using the continuous wave. As a better choice, UWB pulse radar has been generally utilized in movable object reorganization, through-wall imaging and post-earthquake look for and rescue because of its understanding benefits like mighty fitness and distinguished time determination.

With the increasing demand for large-scale data transmission and data security in deep sea observation and detection, Iridium and Beidou dual-mode communication has become the main approach in the field of China’s ocean observation and detection. However, the size and weight of the two antennas are not easy to reduce, which presents a challenge to the buoyancy control system of carriers such as deep sea ARGO buoys. According to the fact that the RDSS L frequency band of Beidou satellite is similar to that of Iridium Satellite system and partly coincides with Iridium frequency band, this paper provides the potential of using Beidou deep sea antenna for Iridium communication. Firstly, the electrical characteristics of existing Iridium and Beidou antennas on the market are measured in microwave anechoic chamber and SATIMO system. Then the outdoor measurements are conducted. The results show that the Beidou deep sea antenna can be used for Iridium communication.

This paper presents a new time of arrival (TOA) estimation technique using an improved energy detection (ED) receiver based on the empirical mode decomposition (EMD) in an impulse radio (IR) 60 GHz millimeter wave (MMW) system. A threshold is employed via analyzing the characteristics of the received energy values with an extreme learning machine (ELM). The effect of the channel and integration period on the TOA estimation is evaluated. Several well-known ED-based TOA algorithms are used to compare with the proposed technique. It is shown that this ELM-based technique has lower TOA estimation error compared to other approaches and provides robust performance with the IEEE 802.15.3c channel models.