Search

The Gaussian noise model and estimators based on least squares (LS) are widely used in target localisation with distributed multiple‐input multiple‐output (MIMO) radar because of their computational efficiency. However, the accuracy of existing LS‐based target localisation algorithms deteriorates sharply in the presence of outliers in the measurements. Thus, a robust solution is developed based on the lp ${l}_{p}$‐norm minimisation criterion and iteratively reweighted least squares (IRLS) for locating a moving target with impulse noise using the angle of arrival (AOA), time delay (TD), and Doppler shift (DS) measurements. First, the AOA, TD, and DS measurement noise models are developed based on the α‐stable distribution. Then, the localisation problem is transformed into an lp ${l}_{p}$‐norm minimisation problem by linearising the AOA, TD, and DS measurement equations. Finally, the lp ${l}_{p}$‐norm minimisation problem is solved using an IRLS method to obtain the target position and estimate the velocity. Moreover, the optimum of the norm order (p) and the Cramér–Rao lower bound for the target position and velocity estimation are derived under α‐stable distributed measurement noise. The simulation results demonstrate that the developed algorithm offers higher accurascy and robustness than the existing ones in the presence of measurement outliers. [ABSTRACT FROM AUTHOR]

The Pd‐catalyzed coupling cyclization of δ,ϵ‐alkenyl oxime with (hetero)aryl and halides is presented, which affords seven membered N,O‐heterocycle, tetrahydro‐1,2‐oxezapines, in moderate to good yields. DFT calculation favors an outer‐sphere anti‐oxypalladation pathway and provides key insights on the reaction mechanism. The reaction represents an unprecedented example of seven‐membered ring formation by heterocyclization. [ABSTRACT FROM AUTHOR]

Radar signal deinterleaving is used to separate interleaved pulse streams in the electronic support measure (ESM) systems. The histogram methods based on the difference in time of arrival (TOA) are more mature in engineering applications than other methods because of their more effortless implementation. In the increasingly complex electronic battlefield, pulse repetition interval (PRI) jitter, and pulse missing are inevitable in the interleaved pulse stream. The TOA differences of pulse trains with PRI jitter distributes in multiple adjacent PRI bins, which results in the significant reduction of the corresponding histogram value. Furthermore, the histogram values of real PRIs vary with pulse missing, which indicates that the histogram lacks robustness to pulse missing. First‐order difference curve based on sorted TOA difference sequence, denoted as FDC‐DTOA, is proposed in this paper to overcome the shortcomings mentioned above. In this method, multi‐order TOA differences are calculated and then sorted in ascending order. Then, FDC‐DTOA is obtained after a first‐order backward difference operation. Finally, an adaptive threshold is applied to FDC‐DTOA to extract candidate PRIs. The simulation results show that the proposed method has remarkable robustness to pulse missing and excellent performance in deinterleaving the pulse stream with PRI jitter. [ABSTRACT FROM AUTHOR]

To avoid decline of FDOA estimation precision caused by relative Doppler companding, Doppler rate has to be considered and estimated jointly with TDOA, phase, and FDOA. However, CRLB of the joint estimation is still unclear. This study addresses on derivation of the CRLB. First, the joint estimation model is constructed. Then, the signal-specific CRLB for any type of signal and a simplified CRLB for stationary and constant-envelope signal are derived, respectively. Finally, as a verification, the derived bound is compared with previous bounds for the special cases of TDOA, phase, and FDOA estimation, which shows that authors' bound is reasonable. In addition to the conventional scenarios of TDOA, phase and FDOA estimation, their bound can also indicate the error characteristic of Doppler rate, which can be used to evaluate estimation performance and forecast location accuracy using Doppler rate. [ABSTRACT FROM AUTHOR]

The target localisation in a multistatic passive radar system using bistatic range measurements from multiple transmitter–receiver pairs is considered. A novel closed-form solution employing multidimensional scaling (MDS) analysis technique is proposed, which is based on the optimisation of a cost function related to the scalar product matrix in the classical MDS framework. The proposed solution is robust to large measurement noise. Simulation results demonstrate the proposed solution achieves a significant performance improvement over existing spherical interpolation, spherical intersection and two-step weighted least squares methods, and attains the Cramer–Rao lower bound at a relatively higher measurement noise level before the threshold effect occurs. [ABSTRACT FROM AUTHOR]

The construction of (Z)‐(hetero)arylethenesulfonyl fluorides was achieved utilizing Iridium photoredox catalysis under UV‐light irradiation. This protocol provided a diverse range of (Z)‐(hetero)arylethenesulfonyl fluorides in moderate to good yields under mild conditions without external additives. The late‐stage transformation of the (Z)‐(hetero)arylethenesulfonyl fluorides comparing with their E‐configuration counterparts was also studied. [ABSTRACT FROM AUTHOR]

A practical Pd‐catalyzed direct dehydroxylative coupling of (hetero)benzylic alcohols with (hetero)arylboronic acids for the constructions of di(hetero)arylmethane derivatives under SO2F2 was described. This new method provided a strategically distinct approach to di(hetero)arylmethane derivatives from readily available and abundant benzylic alcohols under mild condition. [ABSTRACT FROM AUTHOR]

A practical Pd‐catalyzed direct dehydroxylative coupling of (hetero)benzylic alcohols with (hetero)arylboronic acids for the constructions of di(hetero)arylmethane derivatives under SO2F2 was described. This new method provided a strategically distinct approach to di(hetero)arylmethane derivatives from readily available and abundant benzylic alcohols under mild condition. [ABSTRACT FROM AUTHOR]

The [(dppe)RhCl]-catalysed ring expansion of 2-methylbenzocyclobutenone has been proposed to occur by C−C oxidative addition to rhodaindanone, β-hydride elimination, hydrorhodation and C−C reductive elimination. DFT calculations [IEFPCM(1,4-dioxane, 383.15 K)/PBE0/DGDZVP level of theory] here confirm this mechanism. As proposed, oxidative addition into CHMe−CO bond is preferred over the alternative CHMe-aryl insertion. The barriers of oxidative addition, β-hydride elimination hydrorhodation, and reductive elimination are 23.6 (rate-determining), 8.9, 10.4, and 13.1 kcal mol−1, respectively. Therefore, the β-hydride elimination/hydrorhodation steps to/from an octahedral RhIII-hydride serve as a fast equilibrating hydrogen shuffle flanking the two slower C−C bond breaking/making steps. This is consistent with the weak kinetic isotope effect observed experimentally when 2-CH3 and 2-CD3benzocyclobutenone react competitively in a 1:1 ratio. The reaction barriers calculated with more modern, dispersion interaction-corrected methods (SMD/M06 and IEFPCM/ωB97xD) follow identical trends. [ABSTRACT FROM AUTHOR]

A new small molecule with excellent electron-transporting property, namely 9,10-bis(2-( N-octyl-1,8-naphthalimid-4-yl)ethynyl)anthracene ( BNA), is prepared and characterized. A polymer solar cell ( PSC) based on poly(3-hexylthiophene) ( P3HT) and [6,6]-phenyl C61 -butyricacidmethyl ester ( PC61BM) is also fabricated by using BNA as the cathode buffer layer between the Al electrode and photoactive layer, and their influence on the performance of the PSCs is investigated. It is found that the open-circuit voltage ( V oc ), short-circuit current density ( J sc ), and power conversion efficiency ( PCE) of a device with a 6-nm BNA layer improved to 0.63 V, 9.74 mA/cm2, and 3.74%, respectively, which correspond to an increase of 53.6%, 38.0%, and 177% compared to those without the buffer layer. The BNA buffer layer could effectively improve the interfacial contact performance between the Al electrode and photoactive layer, decrease the series resistance, and improve the collection efficiency of carriers. The devices with appropriate thickness of the BNA buffer layer can also replace the common low-work-function metal Ca for increasing the PCE and lifetime of PSCs. [ABSTRACT FROM AUTHOR]

The tensile experiments on the three-dimensional (3D) multi-axial warp knitted (MWK) composites with four types of fiber architecture were performed at room and liquid nitrogen temperatures (as low as -196°C). Macroscopic fracture morphology and SEM micrographs both are examined to understand the deformation and failure mechanism. The results showed that the tensile properties can be affected greatly by the fiber architecture and these decrease significantly with the increase of the fiber orientation angle at room and liquid nitrogen temperatures. Meanwhile, the tensile properties at liquid nitrogen temperature have improved significantly than that of those at room temperature. Moreover, the damage and failure patterns of composites vary with the test temperature. At liquid nitrogen temperature, more microcracks appear and the brittle failure feature becomes more obvious; however, the interfacial adhesion capacity is enhanced significantly. In addition, the fiber architecture has remarkable effect on the failure mechanism at room and liquid nitrogen temperatures. [ABSTRACT FROM AUTHOR]

We report a curved panel using BOA(BM on array) technology in order to solve BM(on CF) shift issue when the flat panel bending curved. Compared with other solution, the BOA structure is more suitable for satisfy curved and flat panel on the same time with sharing one layout. In BOA case, the CF glass only has PS and ITO layer, we using normal PS material as cell process mark like PI or sealant coating instead of traditional BM mark, also we tried to use the PS as UVVA tracing mark to achive photoalignment. The experiment proved that is workable. [ABSTRACT FROM AUTHOR]