Construction of transferable spherically-averaged electron potentials

A new scheme for constructing approximate effective electron potentials within density-functional theory is proposed. The scheme consists of calculating the effective potential for a series of reference systems, and then using these potentials to construct the potential of a general system. To make contact to the reference system the neutral-sphere radius of each atom is used. The scheme can simplify calculations with partial wave methods in the atomic-sphere or muffin-tin approximation, since potential parameters can be precalculated and then for a general system obtained through simple interpolation formulas. We have applied the scheme to construct electron potentials of phonons, surfaces, and different crystal structures of silicon and aluminum atoms, and found excellent agreement with the self-consistent effective potential. By using an approximate total electron density obtained from a superposition of atom-based densities, the energy zero of the corresponding effective potential can be found and the energy shifts in the mean potential between inequivalent atoms can therefore be directly estimated. This approach is shown to work well for surfaces and phonons of silicon.Comment: 8 pages (3 uuencoded Postscript figures appended), LaTeX, CAMP-090594-

A low-cost mechanism to reconfigure the operating frequency band of a Vivaldi antenna for cognitive radio and spectrum monitoring applications

A frequency agile Vivaldi antenna whose operating frequency band can be switched between two selected bands is proposed in this paper for spectrum monitoring and cognitive radio applications. A RF switch is introduced into the back-slot of a Vivaldi antenna to allow switching of the operational band. The realised gains of the antenna are 10.5 dBi in the low band around 3.1 GHz, and 12 dBi in high band around 4.1 GHz. The radiation pattern is stable and its direction is consistent across the two bands. This design can be applied to multiple reconfigurable bands by using more RF switches to tune the desired operating frequency. A set of reliable design equations has been provided as well. This reconfigurable antenna offers improved gain and isolation over multiple, wideband and multiband antennas without increasing the cost and size when compared to those designs reported

Freedom of religion of children in private schools

This article argues against the interpretation that the right to establish private schools includes the right to require religious conformity from non-adherent learners by way of a waiver of their religious freedom. Despite the importance of respecting the rights of religious communities to protect and preserve their faith in private schools, it is submitted that this right cannot be exercised without regard for the religious freedom, dignity and best interests of non-adherent children. As a result, it is submitted that the waiver of the freedom of religion of non-adherent children is not consistent with the values which South African society reveres and, therefore, cannot be enforced. This article suggests that there is a way for the rights of private schools and the rights of the non-adherent child to co-exist in harmony through the application of the reasonable accommodation principle in private schools

Train Monitoring using GSM-R Based Passive Radar

Train detection technologies are universal to all modern railway signal and control systems. They are essential for managing the movement of vehicles across entire transport networks, and to ensure their safe operation. In this paper we investigate the feasibility of a new train monitoring capability based on passive radar technology. The system exploits signal transmissions from the railways’ GSM-Railway (GSM-R) radio communications infrastructure, and has the potential to determine the positions and velocities of trains over any section of a railway network where there is GSM-R coverage. A theoretical ambiguity function analysis on directly measured GSM-R waveforms suggest that targets can be detected with axial range resolutions of approximately 850 m, and velocities down to less than 1 mph. To demonstrate proof-of-concept, a series of experiments were carried out using a software-defined GSM-R passive radar system. The results show the first detections of trains at bistatic ranges of just over 1 km moving at various speeds. There are now hundreds of thousands of miles of railway track covered by GSM-R globally, with many more countries planning to rollout systems nationally. The results therefore imply that GSM-R based passive radar technology could be used to develop low-cost train monitoring capabilities worldwide alongside the existing GSM-R radio communications infrastructure

Positively Verifying Mating of Previously Unverifiable Flight Connectors

Current practice is to uniquely key the connectors, which, when mated, could not be verified by ground tests such as those used in explosive or non-explosive initiators and pyro valves. However, this practice does not assure 100-percent correct mating. This problem could be overcome by the following approach. Errors in mating of interchangeable connectors can result in degraded or failed space mission. Mating of all flight connectors considered not verifiable via ground tests can be verified electrically by the following approach. It requires two additional wires going through the connector of interest, a few resistors, and a voltage source. The test-point voltage V(sub tp) when the connector is not mated will be the same as the input voltage, which gets attenuated by the resistor R(sub 1) when the female (F) and male (M) connectors are mated correctly and properly. The voltage at the test point will be a function of R(sub 1) and R(sub 2). Monitoring of the test point could be done on ground support equipment (GSE) only, or it can be a telemetry point. For implementation on multiple connector pairs, a different value for R(sub 1) or R(sub 2) or both can be selected for each pair of connectors that would result in a unique test point voltage for each connector pair. Each test point voltage is unique, and correct test point voltage is read only when the correct pair is mated correctly together. Thus, this design approach can be used to verify positively the correct mating of the connector pairs. This design approach can be applied to any number of connectors on the flight vehicle

Pharmaceutical Studies and Therapeutic Uses of \u3cem\u3ePlumbago Zeylanica\u3c/em\u3e L. Roots (Chitraka, Chitramulamu)

The pharmaceutical studies and therapeutic uses of Plumbago zeylanica, in fresh root and as well as dry drug (root), were studied. The fresh root drug preparation includes Chitraka swarasam (freshly expressed juice), Chitraka kalkam (paste) and their therapeutic uses. Dry drug reveals preparation of Chitraka churnam (powder), Chitrakadi vati (tablets), Chitrakadi dutika (pills), Chitraka ghritam (ghee preparation), Chitraka quatham (decoction), Chitraka himam (cold infusion), Chitraka Phantam (hot infusion) and their therapeutic use for the treatment of various ailments was recorded

Signs of life detection using wireless passive radar

Non-contact devices for monitoring signs of life have attracted a lot of attention in recent years for applications in security, emergency and disaster situations. Current devices however, generally utilize bespoke active systems to transmit large bandwidth signals. In this paper, a real-Time phase extraction method based on passive Wi-Fi radar is proposed for detecting the chest movements associated with a person breathing. Since the monitored movements are of low amplitude and small Doppler shift, this method uses the phase variation rather than traditional range-Doppler processing. The processing is based on time domain cross correlation, with the addition of a Hampel filter for outlier detection and removal. In this paper the basic passive Wi-Fi model and limitations of traditional cross ambiguity function for signs of life detection are first introduced. The phase extraction method is then described followed by experimental results and analysis. Detection of breathing for a stationary person is shown in both in-room and through wall scenarios using both the Wi-Fi beacon and data transmissions. This is believed to be the first demonstration of signs of life detection using phase extraction in passive radar and extends the capability of such systems into a wide range of new applications

A low-cost through-the-wall FMCW radar for stand-off operation and activity detection

In this paper we present a new through-wall (TW) FMCW radar system. The architecture of the radar enables both high sensitivity and range resolutions of <1.5 m. Moreover, the radar employs moving target indication (MTI) signal processing to remove the problematic primary wall reflection, allowing higher signal-to- noise and signal-to-interference ratios, which can be traded-off for increased operational stand-off. The TW radar operates at 5.8 GHz with a 200 MHz bandwidth. Its dual-frequency design minimises interference from signal leakage, and permits a baseband output after deramping which is digitized using an inexpensive 24-bit off-the-shelf sound card. The system is therefore an order of magnitude lower in cost than competitor ultrawideband (UWB) TW systems. The high sensitivity afforded by this wide dynamic range has allowed us to develop a wall removal technique whereby high-order digital filters provide a flexible means of MTI filtering based on the phases of the returned echoes. Experimental data demonstrates through-wall detection of individuals and groups of people in various scenarios. Target positions were located to within ±1.25 m in range, allowing us distinguish between two closely separated targets. Furthermore, at 8.5 m standoff, our wall removal technique can recover target responses that would have otherwise been masked by the primary wall reflection, thus increasing the stand-off capability of the radar. Using phase processing, our experimental data also reveals a clear difference in the micro-Doppler signatures across various types of everyday actions

Transfer Learning from Audio Deep Learning Models for Micro-Doppler Activity Recognition

This paper presents a mechanism to transform radio micro-Doppler signatures into a pseudo-audio representation, which results in significant improvements in transfer learning from a deep learning model trained on audio. We also demonstrate that transfer learning from a deep learning model trained on audio is more effective than transfer learning from a model trained on images, which suggests machine learning methods used to analyse audio can be leveraged for micro-Doppler. Finally, we utilise an occlusion method to gain an insight into how the deep learning model interprets the micro-Doppler signatures and the subsequent pseudo-audio representations

Activity Recognition Based on Micro-Doppler Signature with In-Home Wi-Fi

Device free activity recognition and monitoring has become a promising research area with increasing public interest in pattern of life monitoring and chronic health conditions. This paper proposes a novel framework for inhome Wi-Fi signal-based activity recognition in e-healthcare applications using passive micro-Doppler (m-D) signature classification. The framework includes signal modeling, Doppler extraction and m-D classification. A data collection campaign was designed to verify the framework where six m-D signatures corresponding to typical daily activities are sucessfully detected and classified using our software defined radio (SDR) demo system. Analysis of the data focussed on potential discriminative characteristics, such as maximum Doppler frequency and time duration of activity. Finally, a sparsity induced classifier is applied for adaptting the method in healthcare application scenarios and the results are compared with those from the well-known Support Vector Machine (SVM) method