We have demonstrated electrical spin-injection from GaCrN dilute magnetic semiconductor (DMS) in a GaN-based spin light emitting diode (spin-LED). The remanent in-plane magnetization of the thin-film semiconducting ferromagnet has been used for introducing the spin polarized electrons into the non-magnetic InGaN quantum well. The output circular polarization obtained from the spin-LED closely follows the normalized in-plane magnetization curve of the DMS. A saturation circular polarization of ∼2.5% is obtained at 200 K.

Handwritten signatures are widely utilized as a form of personal recognition. However, they have the unfortunate shortcoming of being easily abused by those who would fake the identification or intent of an individual which might be very harmful. Therefore, the need for an automatic signature recognition system is crucial. In this paper, a signature recognition approach based on a probabilistic neural network (PNN) and wavelet transform average framing entropy (AFE) is proposed. The system was tested with a wavelet packet (WP) entropy denoted as a WP entropy neural network system (WPENN) and with a discrete wavelet transform (DWT) entropy denoted as a DWT entropy neural network system (DWENN). Our investigation was conducted over several wavelet families and different entropy types. Identification tasks, as well as verification tasks, were investigated for a comprehensive signature system study. Several other methods used in the literature were considered for comparison. Two databases were used for algorithm testing. The best recognition rate result was achieved by WPENN whereby the threshold entropy reached 92%.

In this work, a gamma ray Compton backscatter technique is used for imaging defects and thickness variations in insulated pipes and metal plates containing depressions of various diameters and at various depths from one side of the object. The scattered radiation was measured by a scintillation detector that scans the object using a two-dimensional mechanical scanning system. The gamma spectrum was displayed with a multichannel analyzer (MCA), and the energy window width was selected so that only Compton single scatter counts were measured. Images were constructed using the LabVIEW computer program. Successful images of defects on the outer surface of the object under the insulation were obtained, and the system was found to be able to detect wall thickness changes in large pipes with walls more than 15 mm thick. Low activity sources of 10⁸ Bq (a few mCi) were used, and the dose rate near the surface is four orders of magnitude lower than conventional industrial radiography sources, permitting it to be much safer.

Gamma radiography is used to monitor the corrosion of pipelines in remote locations; usually high radioactivity (10¹¹–10¹² Bq) is used. The technique is also not useful for imaging pipes with thick walls or large vessel walls. In this work, Compton backscattered radiation was used for the wall-thickness determination and corrosion imaging of pipe and flat materials using extremely-low-activity sources with radioactivities on the order of 10⁴–10⁵ Bq. A two-dimensional scanning system was designed to scan object surfaces, and the signals from a NaI(Tl) scintillation detector were fed into a computer for image construction using the LabView program. Thicknesses greater than 1 cm and 1.5 cm could be measured for Fe and Al and for polyvinyl chloride (PVC) and poly methyl methacrylate (PMMA), respectively. It was also possible to detect changes of less than 1 mm in depression depth for depressions measuring 3 mm in diameter. One- and two-dimensional images artificial defects on a pipe surface were successfully constructed.

Gold codes have many important applications, particularly in spread-spectrum code-division multiple-acess (CDMA) systems. The generation of Gold codes and the measurement of their correlation properties using some simple circuits are described in this paper. In particular, a circuit for the generation of m-sequences and Gold codes of 31 bits length and arbitrary phases, as well as a special digital matched filter circuit that is used to measure the correlation properties of these codes, are described in detail. Examples of the measured autocorrelation and cross-correlation functions of Gold codes are presented and compared with the corresponding computer generated results.