Spl Theta Research Articles

Using a healing robot for the scientific study of Shirodhara

One of the critical problems in the study of physiotherapy of Oriental medicine is not being able to use the same reproducible stimulation, especially in Ayurvedic oil treatments. To address this problem, we developed a healing robot which conducts shirodhara (an oil treatment) in a computerized reproducible manner. The physio-psychological changes during taila dhara conducted by the healing robot and an estimated psychological experiences during taila dhara by psychometric studies of anxiety and altered states of consciousness (ASC) were studied. The physiological changes of the practitioners themselves were checked. Sixteen healthy adult females (ages 21-56, 33 /spl plusmn/ 9 years) signed informed consent and participated in this study. During shirodhara the monitoring items for the subjects were: blood pressure and intermittent blood pressure, electrocardiogram (ECG) R-R intervals, expired gas analysis, impedance cardiography and electroencephalogram (EEG). The single EEG (C3 lead) of the technician was recorded at the same time, and respiratory movement of the chests of both subject and technician were also recorded. In the active studies, shirodhara was performed by a machine with a pumping and heating system. The subject's feelings during shirodhara showed deep restfulness with less anxiety - as if the subjects were between the sleep and awake states. Shirodhara induced bradycardia and the relative suppression of LF/HF power spectrum density, which indicated lowered sympathetic tone. Expired gas analysis showed a decreased tidal volume and CO/sub 2/ excretion. The EEG showed the slowing of the /spl alpha/ wave, an increase in /spl alpha/ and /spl theta/ activity and an increase in right-left coherence. These metabolic, ECG, and EEG findings support the reported experiences of relaxed and low metabolic states during shirodhara. Physiological changes during shirodhara were similar to those of meditation, including /spl alpha/-wave dominance in the frontal area and a decrease in heart rate and CO/sub 2/ excretion. These findings indicated a change in the function of the frontal lobe, limbic system, brain stem, and autonomic nervous system. On the other hand, the EEGs of the technicians of the manual shirodhara showed an increase in their stressful condition, which may also justify the utility of the healing robot as an assistant for the technicians.

On the Scaling Laws of Dense Wireless Sensor Networks: The Data Gathering Channel

We consider dense wireless sensor networks deployed to observe arbitrary random fields. The requirement is to reconstruct an estimate of the random field at a certain collector node. This creates a many-to-one data gathering wireless channel. In this note, we first characterize the transport capacity of many-to-one dense wireless networks subject to a constraint on the total average power. In particular, we show that the transport capacity scales as /spl Theta/(log(N)) when the number of sensors N grows to infinity and the total average power remains fixed. We then use this result along with some information-theoretic tools to derive sufficient and necessary conditions that characterize the set of observable random fields by dense sensor networks. In particular, for random fields that can be modeled as discrete random sequences, we derive a certain form of source/channel coding separation theorem. We further show that one can achieve any desired nonzero mean-square estimation error for continuous, Gaussian, and spatially bandlimited fields through a scheme composed of single-dimensional quantization, distributed Slepian-Wolf source coding, and the proposed antenna sharing strategy. Based on our results, we revisit earlier conclusions about the feasibility of data gathering applications using dense sensor networks.

R-z two-dimensional numerical Simulations of a frozen inert gas plasma MHD Generator

In a magnetohydrodynamics (MHD) power generation with a frozen inert gas plasma (FIP), the effect of the nonuniformity of the inlet plasma in the direction perpendicular to walls on the performance and the comparison of the performance with r-/spl theta/ two-dimensional (2-D) numerical simulations are examined with r-z 2-D ones. The inlet nonuniformity of an ionization degree is kept throughout the channel and even in the boundary layer the state of the FIP is realized without an ionization instability. When the inlet ionization degree near the walls is higher than that in the main flow, the enthalpy extraction ratio decreases because the strong MHD interaction near the wall leads to the development of the boundary layer. On the other hand, it increases for the inverse distribution at the channel inlet, even if the introduced total inlet ionization degree is the same. In comparison with the results obtained from the r-/spl theta/ simulation, the development of the boundary layer results in the deterioration of the performance, and the optimal condition shifts to the low inlet ionization degree and the high load resistance.

Spatial filter-based absorbing boundary for the 2-D digital waveguide mesh

The digital waveguide mesh is a method for simulating wave propagation, for example, in an acoustic system. Research on the boundary conditions has been going on for years, but adequate solutions for absorbing boundaries have not yet been presented for the digital waveguide mesh. In this work, a new method for constructing absorbing boundaries for a two-dimensional (2-D) rectangular mesh is introduced. With the use of the proposed numerically optimized spatial filtering with an interpolated mesh structure, the reflection was diminished to under -25 dB at incidence angles |/spl theta/|/spl les/79.26/spl deg/ on a frequency band limited only at the very lowest and highest ends.

A novel fiber alignment shift measurement and correction technique in laser-welded laser module packaging

A novel measurement and correction technique employing an ultra-high-precision laser displacement meter (LDM) with a 20-nm resolution to probe the postweld-shift (PWS)-induced fiber alignment shifts in laser-welded laser module packaging is presented. The results show that the direction and magnitude of the fiber alignment shifts induced by the PWS in laser-welded laser module packaging can be quantitatively determined by four parameters: the lateral position (r), the position angle (/spl alpha/), the swing angle (/spl theta/), and the tilt angle (/spl psi/). Further studies show that the deformation of the lateral shift and the position angle are the dominant mechanisms that determine the fiber alignment shifts induced by the PWS. This clearly indicates that the PWS can be quantitatively corrected timely by applying a single weld spot on the negative lateral shift and the position angle to compensate for the fiber alignment shifts. In comparison with previous studies of the PWS correction by a qualitatively estimated technique, this LDM technique has significantly provided an important tool for quantitative measurement and correction to the effect of the PWS on the fiber alignment shifts in laser-welded laser module packaging. Therefore, the reliable laser modules with high yield and high performance used in low-cost lightwave transmission systems may be developed and fabricated.

Lumped-Element Isolator With Lower Symmetrical Configuration of Three Windings

Ideal isolator conditions are derived using circuit analysis in a lumped-element isolator with three windings at angles of /spl theta/ and /spl phi/. The angle /spl theta/ can be arbitrary; however, /spl phi/ is restricted to lie on the bisector of cross-angle /spl theta/ or the supplementary angle of /spl theta/. We found that the isolator with /spl theta/=/spl phi/=60 [deg] behaves the same as the one with conventional structure with /spl theta/=/spl phi/=120 [deg]. However, the former has a 0/spl deg/ phase shift and the latter a 180/spl deg/ phase shift between the input and output. The theoretical prediction was experimentally confirmed with an 800-MHz-band isolator.

A Half-Moon Antenna

This work presents a half-moon antenna (HMA), which is composed of two semi-circular top and bottom conducting plates joined by a rectangular conducting plate. The HMA has a wide radiation beam. Radiation in the y-z plane (in the E plane) is hemispherical with a half-power beam width (HPBW) of more than 200/spl deg/. Radiation in the x-y plane (in the H plane) forms a sector beam with an HPBW of more than 100/spl deg/. To reduce the backward radiation and improve the gain, chokes are added to the HMA. An increase in the gain of approximately 1 dB is obtained. In order to obtain a tilted beam, the radius of the bottom plate is reduced. The maximum beam direction of the tilted beam /spl theta//sub max/ is not sensitive to frequency. Within a frequency range of 11 to 14 GHz (24%), /spl theta//sub max/=167/spl deg//spl plusmn/2/spl deg/. The gain is found to be G=9.5/spl plusmn/0.5 dBi within this same frequency range.

Moisture Determination in Single Peanut Pods by Complex RF Impedance Measurement

An assessment was made of estimating the moisture content (mc) of single peanut pods (in-shell peanuts) by measuring the complex impedance of a parallel-plate capacitor with a single pod between the plates. Capacitance (C), phase angle (/spl theta/) and/or dissipation factor (D) were measured at 1.0 and 5.0 MHz, and the measured values at these two frequencies were used in a derived empirical equation to calculate the mc. Previous research had determined that the mc of single and small samples of shelled peanuts (kernels) could be determined by similar measurements at 1 and 4.5 MHz. In this paper, the mc of the pods tested was between 5% and 25%. The predicted mc of the pods was within 1% of the standard air-oven values for about 85% of the single pods.

Soil Moisture Retrievals From Biangular L-Band Passive Microwave Observations

A simple approach for correcting the effect of vegetation in the estimation of soil moisture (w/sub S/) from L-band passive microwave observations is presented in this study. The approach is based on statistical relationships, calibrated from simulated datasets, which requires only two observations made at distinct incidence angles (/spl theta//sub 1/,/spl theta//sub 2/). A sensitivity study was carried out, and best retrieval remote sensing configurations, in terms of polarization and couple of incidence angles (/spl theta//sub 1/,/spl theta//sub 2/), were investigated. Best estimations of w/sub S/ could be made at H polarization, for /spl theta//sub 1/ varying between 15/spl deg/ and 30/spl deg/, and with a difference (/spl theta//sub 2/-/spl theta//sub 1/) larger than 30/spl deg/. The method was tested against two experimental datasets acquired over crop fields (soybean and wheat). The average accuracy in the soil moisture retrievals during the whole crop cycle was found to be about 0.05 m/sup 3//m/sup 3/ for both crops.

An Insulator-Metallic Phase Transition Cascade for Improved Electromagnetic Flux-Compression in<tex>$theta $</tex>-Pinch Geometry

During an initial phase of an ongoing research program at Loughborough University, ultrahigh magnetic fields of up to 300 T (3 MG) have been generated. These have been produced using only 63 kJ from a fast capacitor bank to implode an aluminum liner in a /spl theta/-pinch geometry, and 14.7 kJ from a slow capacitor bank to provide an initial magnetic field. The paper analyzes various ways of improving both the /spl theta/-pinch magnetic flux-compression efficiency and its reproducibility. As a practical illustration, experimental evidence is presented to demonstrate the benefits obtained from the use of an insulator-metallic phase transition cascade made from powder aluminum.

Unifying mesh- and tree-based programmable interconnect

We examine the traditional, symmetric, Manhattan mesh design for field-programmable gate-array (FPGA) routing along with tree-of-meshes (ToM) and mesh-of-trees (MoT) based designs. All three networks can provide general routing for limited bisection designs (Rent's rule with p<1) and allow locality exploitation. They differ in their detailed topology and use of hierarchy. We show that all three have the same asymptotic wiring requirements. We bound this tightly by providing constructive mappings between routes in one network and routes in another. For example, we show that a (c,p) MoT design can be mapped to a (2c,p) linear population ToM and introduce a corner turn scheme which will make it possible to perform the reverse mapping from any (c,p) linear population ToM to a (2c,p) MoT augmented with a particular set of corner turn switches. One consequence of this latter mapping is a multilayer layout strategy for N-node, linear population ToM designs that requires only /spl Theta/(N) two-dimensional area for any p when given sufficient wiring layers. We further show upper and lower bounds for global mesh routes based on recursive bisection width and show these are within a constant factor of each other and within a constant factor of MoT and ToM layout area. In the process we identify the parameters and characteristics which make the networks different, making it clear there is a unified design continuum in which these networks are simply particular regions.

3-D isotropic imaging of environmental sources using a compact gamma camera

In this work, the three-dimensional (3-D) position information of a radiation source is determined by a compact gamma ray imaging system. Two-dimensional (2-D) gamma ray images were obtained from different positions by the gamma camera and the third dimension, the distance between the detector and the radiation source, was calculated using triangulation. Additionally, a CCD camera is attached to the top of the gamma camera and provides associated 2-D visual information. The inferred distances from the center of the two measurement points and a radiation source had less than a 5% error for sources within 3 m and /spl plusmn/45/spl deg/ FOV. From the measured distances and camera intrinsic efficiencies /spl epsiv/(/spl theta/,/spl phi/) from MCNP simulations, the activity of the source was normally determined within 80% of the true value depending upon source position. The parallax between the two visual images was corrected using the inferred distance between the detector and the radiation source. The radiation image from gamma camera and the visual image from CCD camera are superimposed into one combined image using a maximum-likelihood (ML) algorithm to make the image alignment more precise. Energy dependent response functions were found to be better than a fixed energy response function for ML image processing.

Theoretical and Experimental Analysis of Heuristics for the “Freeze-Tag” Robot Awakening Problem

In the "freeze-tag" problem, we are given a swarm of n sleeping (frozen or inactive) robots and a single awake (active) robot. The goal is to awaken all robots in the shortest possible time. A robot is awakened when an active robot "touches" it. The goal is to compute an optimal awakening schedule such that all robots are awake by time t/sup */, for the smallest possible value of t/sup */. We devise and test a variety of heuristic strategies on geometric and network datasets. Our experiments show that all of the strategies perform acceptably well, with the simple greedy strategy performing particularly well. A theoretical analysis of the greedy strategy gives a tight approximation bound of /spl Theta/(/spl radic/logn) for points in the plane. We show more generally a tight performance bound of /spl Theta/((logn)/sup 1-1/d/) in d dimensions. The geometric case contrasts with the case of general metric spaces, where greedy is known to have a /spl Theta/(logn) approximation factor, and no method is known to achieve an approximation factor of o(logn).

Application of the theory of optimal experiments to adaptive electromagnetic-induction sensing of buried targets

A mobile electromagnetic-induction (EMI) sensor is considered for detection and characterization of buried conducting and/or ferrous targets. The sensor may be placed on a robot and, here, we consider design of an optimal adaptive-search strategy. A frequency-dependent magnetic-dipole model is used to characterize the target at EMI frequencies. The goal of the search is accurate characterization of the dipole-model parameters, denoted bythe vector theta; the target position and orientation are a subset of theta. The sensor position and operating frequency are denoted by the parameter vector p and a measurement is represented by the pair (p, O), where O denotes the observed data. The parametersp are fixed for a given measurement, but, in the context of a sequence of measurements p may be changed adaptively. In a locally optimal sequence of measurements, we desire the optimal sensor parameters, P(N+1) for estimation of theta, based on the previous measurements (p(n), On)n=1,N. The search strategy is based on the theory of optimal experiments, as discussed in detail and demonstrated via several numerical examples.

A Fast Algorithm for Calculating the Radiation Pattern in the Longitudinal Plane of Antennas With Cylindrical Structure by Applying Asymptotic Waveform Evaluation in a Spectrum of Two-Dimensional Solutions

When dealing with electromagnetic problems of small three-dimensional (3-D) elements, such as dipole, microstrip patches and slots, in the vicinity of two-dimensional (2-D) structures, it is very efficient to find the radiation characteristics of the 3-D elements by using a spectrum of 2-D solutions (S2DS). Only one 2-D solution in the spectral domain is needed to obtain the radiation pattern in the transverse plane defined by /spl theta/=90/spl deg/. For the radiation in a longitudinal plane defined by a fixed azimuth angle /spl phi/, one 2-D problem has to be solved for each value of the polar angle /spl theta/. This paper presents a fast algorithm by which the radiation pattern in the longitudinal plane can be computed more efficiently. The algorithm applies the method of asymptotic waveform evaluation (AWE) in the 2-D spectral domain. For the cases shown in the paper, the algorithm needs only three 2-D solutions to determine the complete radiation pattern in the longitudinal plane.

Finite-Memory Universal Prediction of Individual Sequences

The problem of predicting the next outcome of an individual binary sequence under the constraint that the universal predictor has a finite memory, is explored. In this analysis, the finite-memory universal predictors are either deterministic or random time-invariant finite-state (FS) machines with K states (K-state machines). The paper provides bounds on the asymptotic achievable regret of these constrained universal predictors as a function of K, the number of their states, for long enough sequences. The specific results are as follows. When the universal predictors are deterministic machines, the comparison class consists of constant predictors, and prediction is with respect to the 0-1 loss function (Hamming distance), we get tight bounds indicating that the optimal asymptotic regret is 1/(2K). In that case of K-state deterministic universal predictors, the constant predictors comparison class, but prediction is with respect to the self-information (code length) and the square-error loss functions, we show an upper bound on the regret (coding redundancy) of O(K/sup -2/3/) and a lower bound of /spl Theta/(K/sup -4/5/). For these loss functions, if the predictor is allowed to be a random K-state machine, i.e., a machine with random state transitions, we get a lower bound of /spl Theta/(1/K) on the regret, with a matching upper bound of O(1/K) for the square-error loss, and an upper bound of O(logK/K) Throughout the paper for the self-information loss. In addition, we provide results for all these loss functions in the case where the comparison class consists of all predictors that are order-L Markov machines.

On the implementation of unreliable failure detectors in partially synchronous systems

Unreliable failure detectors were proposed by Chandra and Toueg as mechanisms that provide information about process failures. Chandra and Toueg defined eight classes of failure detectors, depending on how accurate this information is, and presented an algorithm implementing a failure detector of one of these classes in a partially synchronous system. This algorithm is based on all-to-all communication and periodically exchanges a number of messages that is quadratic on the number of processes. We study the implementability of different classes of failure detectors in several models of partial synchrony. We first show that no failure detector with perpetual accuracy (namely, P, Q, S, and W) can be implemented in these models in systems with even a single failure. We also show that, in these models of partial synchrony, it is necessary a majority of correct processes to implement a failure detector of the class /spl theta/ proposed by Aguilera et al. Then, we present a family of distributed algorithms that implement the four classes of unreliable failure detectors with eventual accuracy (namely, /spl diams/P, /spl diams/Q, /spl diams/S, and /spl diams/W). Our algorithms are based on a logical ring arrangement of the processes, which defines the monitoring and failure information propagation pattern. The resulting algorithms periodically exchange at most a linear number of messages.

C-Axis Oriented Ba-Ferrite Thin Film With Perpendicular Anisotropy Deposited on Si&amp;lt;tex&amp;gt;$_3$&amp;lt;/tex&amp;gt;N&amp;lt;tex&amp;gt;$_4$&amp;lt;/tex&amp;gt;Substrate

Si/sub 3/N/sub 4/, a new substrate as well as thermally oxidized SiO/sub 2//Si wafer substrate were used to prepare hexagonal Barium ferrite (BaM) thin films by facing target sputtering system. At substrate temperature (Ts) of 600/spl deg/C, the intensities of BaM [00l] planes in X-ray diffraction diagrams were much stronger in the case of Si/sub 3/N/sub 4/ substrate than that of SiO/sub 2//Si wafer substrate. The value of /spl Delta//spl theta//sub 50/ was found about 2.28/spl deg/ for 25-nm thickness of BaM deposited on Si/sub 3/N/sub 4/. Then, Ts was reduced to 525/spl deg/C. Perpendicular coercivity (Hc/sub perp/) and squareness ratio (S/sub perp/) were higher in the case of Si/sub 3/N/sub 4/ substrate even at 525/spl deg/C. The maximum value of Hc/sub perp/=3.25 kOe and S/sub perp/=0.7 was found for the film of 35 nm. It was found that Si/sub 3/N/sub 4/ not only reduces the Ts of BaM during in-situ deposition but also increases the perpendicular anisotropy of BaM thin film.

Universally Attainable Error Exponents for Rate-Distortion Coding of Noisy Sources

Consider the problem of rate-constrained reconstruction of a finite-alphabet discrete memoryless signal X/sup n/=(X/sub 1/,...,X/sub n/), based on a noise-corrupted observation sequence Z/sup n/, which is the finite-alphabet output of a discrete memoryless channel (DMC) whose input is X/sup n/. Suppose that there is some uncertainty in the source distribution, in the channel characteristics, or in both. Equivalently, suppose that the distribution of the pairs (X/sub i/,Z/sub i/), rather than completely being known, is only known to belong to a set /spl Theta/. Suppose further that the relevant performance criterion is the probability of excess distortion, i.e., letting X/spl circ//sup n/(Z/sup n/) denote the reconstruction, we are interested in the behavior of P/sub /spl theta//(/spl rho/(X/sup n/,X/spl circ//sup n/(Z/sup n/))>d/sub /spl theta//), where /spl rho/ is a (normalized) block distortion induced by a distortion measure and P/sub /spl theta// denotes the probability measure corresponding to the case where (X/sub i/,Z/sub i/)/spl sim//spl theta/, /spl theta//spl isin//spl Theta/. Since typically this probability will either not decay at all or do so at an exponential rate, it is the rate of this decay which we focus on. More concretely, for a given rate R /spl ges/ 0 and a family of distortion levels {d/sub /spl theta//}/sub /spl theta//spl isin//spl Theta//, we are interested in families of exponential levels {I/sub /spl theta//}/sub /spl theta//spl isin//spl Theta// which are achievable in the sense that for large n there exist rate-R schemes satisfying -1/nlog P/sub /spl theta// (/spl rho/(X/sup n/, X/spl circ//sup n/(Z/sup n/)) > d/sub /spl theta//) /spl ges/ I/sub /spl theta//, for all /spl theta/ /spl isin/ /spl Theta/. Our main result is a complete single-letter characterization of achievable levels {I/sub /spl theta//}/sub /spl theta//spl isin//spl Theta// per any given triple (/spl Theta/,R,{d/sub /spl theta//}/sub /spl theta//spl isin//spl Theta//). Equipped with this result, we later turn to addressing the question of the right choice of {I/sub /spl theta//}/spl theta//spl isin//spl Theta/. Relying on methodology recently put forth by Feder and Merhav in the context of the composite hypothesis testing problem, we propose a competitive minimax approach for the choice of these levels and apply our main result for characterizing the associated key quantities. Subsequently, we apply the main result to characterize optimal performance in a Neyman-Pearson-like setting, where there are two possible noise-corrupted signals. In this problem, the goal of the observer of the noisy signal, rather than having to determine which of the two it is (as in the hypothesis testing problem), is to reproduce the underlying clean signal with as high a fidelity as possible (e.g., lowest number of symbol errors when distortion measure is Hamming), under the assumption that one source is active, while operating at a limited information rate R and subject to a constraint on the fidelity of reconstruction when the other source is active. Finally, we apply our result to characterize a sufficient condition for the source class /spl Theta/ to be universally encodable in the sense of the existence of schemes attaining the optimal distribution-dependent exponent, simultaneously for all sources in the class. This condition was shown in an earlier work to suffice for universality in expectation.

FEM Analysis of Three Directional Strain States Under Applied Tensile Stress for Various Composite Superconductors

Composite superconductors such as Cu/Nb/sub 3/Sn and Ag/Bi-oxides are subjected to thermally-induced residual strain by other component materials due to the around 1,000 K temperature difference between the reaction temperature and the cryogenic temperatures, and to applied tensile strain by the hoop stress of longitudinal (z) direction during the coil operation. To clarify especially the radial (r) and tangential (/spl theta/) strain behaviors including z-strain, we analyzed elastic-plastically multi-core model by computing of FEM for various composite conductors. As a result, applied tensile stress on the z-direction of the composite conductor gave monotonous decrease of thermally-induced rand /spl theta/-strains, which changed tensile to compressive strain. With increase in the z-strain effective strain showed the minimum value, not zero, at around z-strain-free state. Moreover it was found that all conductors are classified into three types by combination of component materials.