OFF Mode Research Articles

Geometric conductive filament confinement by nanotips for resistive switching of HfO2-RRAM devices with high performance.

Filament-type HfO2-based RRAM has been considered as one of the most promising candidates for future non-volatile memories. Further improvement of the stability, particularly at the “OFF” state, of such devices is mainly hindered by resistance variation induced by the uncontrolled oxygen vacancies distribution and filament growth in HfO2 films. We report highly stable endurance of TiN/Ti/HfO2/Si-tip RRAM devices using a CMOS compatible nanotip method. Simulations indicate that the nanotip bottom electrode provides a local confinement for the electrical field and ionic current density; thus a nano-confinement for the oxygen vacancy distribution and nano-filament location is created by this approach. Conductive atomic force microscopy measurements confirm that the filaments form only on the nanotip region. Resistance switching by using pulses shows highly stable endurance for both ON and OFF modes, thanks to the geometric confinement of the conductive path and filament only above the nanotip. This nano-engineering approach opens a new pathway to realize forming-free RRAM devices with improved stability and reliability.

Composed planar Hall effect sensors with dual-mode operation

We present a composed planar Hall effect sensor with two modes of operation: (a) an ON mode where the composed sensor responds to magnetic field excitations similarly to the response of a regular planar Hall effect sensor, and (b) an OFF mode where the response is negligible. The composed planar Hall effect sensor switches from the OFF mode to the ON mode when it is exposed to a magnetic field which exceeds a certain threshold determined by the sensor design. The features of this sensor make it useful as a switch triggered by magnetic field and as a sensing device with memory, as its mode of operation indicates exposure to a magnetic field larger than a certain threshold without the need to be activated during the exposure itself.

A Reconfigurable Multiband Antenna for RFID and GPS Applications

A C-shaped patches loaded with dipole antenna designed for multiband antenna is proposed. The antenna can be reconfigured as single band at 1.2275 GHz for GPS applications and dual-band frequencies at UHF band (850 MHz–930 MHz) and ISM band (2.41 GHz–2.54 GHz) required in RFID applications. The performance of the antenna involves changing the switches to ON or OFF mode by controlling switches. By adjusting the dimension of C-shaped patch, a dual-band frequency of 0.89 GHz and 2.46 GHz is performed. The antenna’s gains are 2 dBi and 3.2 dBi for lower and upper bands respectively. The length slot and length of C-shaped patch can be varied to adjust the desired upper frequency as well as the bandwidth. Moreover, the lower frequency can be tuned by varying the dipole arms for both elements. Nevertheless, the dipole antenna operated as single band when the switches are OFF at frequency resonance is 1.2275 GHz with 2.06 dBi of gain. The total efficiency for single and dual band is greater than 90 %. The design methodology and antenna measurement results are both presented and discussed in this paper. DOI: http://dx.doi.org/10.5755/j01.eee.21.6.13760

Energy Efficient Smart Sensor Network Routing Protocol using Node Scheduling

needs are going more technology dependent in last decade. Technology touches live everywhere and also reach the area where humans unable to reach. One of Such important application is Wireless Sensor Networks (WSNs). This helps to collect data from different conditions where human faces challenges to gather information about atmosphere or environment. Apart of its advantage, WSN suffer from many different challenges like limited sensor node electric capacity, pattern of node deployment, data sending mechanism etc. To manage WSN with optimum resource utilization various data transmission methods have been given in recent years. This paper proposed another better method for improving network life span and increase stability of WSN. Proposed method manages all sensor nodes energy power within intelligence manor by using ON-OFF scheduling of node data transmission. Few nodes in ON state sense data and send to base station for one round of data transmission while other nodes are in power saving OFF mode by doing nothing neither sense nor transmit data. But for next round nodes are in ON status nodes goes to OFF power saving modes to save power and OFF mode nodes sense and send data to base station. This method is compared with other technique using same parameter while simulation and proposed method outperform better in all aspects of WSN comparison. Keywordsefficient, Data transmission protocol, ON mode, OFF mode, WSN, scheduling

On the Nonvolatile Performance of Flip-Flop/SRAM Cells With a Single MTJ

In this brief, three nonvolatile flip-flop (FF)/SRAM cells that utilize a single magnetic tunneling junction (MTJ) as nonvolatile resistive element are proposed. These cells have the same core (i.e., 6T) but they employ different numbers of MOSFETs to implement the so-called instantly ON, normally OFF mode of operation. The additional transistors are utilized for the restore operation to ensure that the data stored in the nonvolatile circuitry can be written back into the FF core once the power is made available. These three cells (7T, 9T, and 11T) are extensively analyzed in terms of their operations in 32 nm technology, such as operational delays (for the write, read, and restore operations), the static noise margin (SNM), critical charge and process variations (in both the MOSFETs and the resistive element). Simulation results show that an increase in the number of MOSFETs in the cells causes improvements in critical charge and tolerance to process variations at the expense of an increase in power dissipation. The SNM and the delay of the restore operation, however, do not necessarily increase with the number of MOSFETs in the cell, but rather on the control of access to the storage nodes from the single MTJ.

Selective naked-eye detection of Hg²⁺ through an efficient turn-on photoinduced electron transfer fluorescent probe and its real applications.

A simple molecular fluorescent probe 5 has been designed and synthesized by appending anthracene and benzhydryl moieties through a piperazine bridge. The probe upon interaction with different metal ions showed high selectivity and sensitivity (2 ppb) for Hg(2+) through fluorescence "turn-on" response in HEPES buffer. The significant fluorescence enhancement (~10-fold) is attributable to PET arrest due to complexation with nitrogen atoms of the piperazine unit and Hg(2+) in 1:2 stoichiometry, in which a naked-eye sensitive fluorescent blue color of solution changed to a blue-green (switched-on). As a proof of concept, promising prospects for application in environmental and biological sciences 5 have been utilized to detect Hg(2+) sensitively in real samples, on cellulose paper strips, in protein medium (like BSA), and intracellularly in HeLa cells. Moreover, the optical behavior of 5 upon providing different chemical inputs has been utilized to construct individual logic gates and a reusable combinational logic circuit. The combinational circuit (switch ON mode; OR logic gate) is easily resettable to the original position (switch OFF mode; INHIBIT logic gate) by applying reset chemical inputs (OH(-) and PO4(3-)) with great reproducibility.

English

This paper further improves the previous work made to reduce the leakage power of electric home appliances. All the electric appliances consume electricity when they are in standby mode. It is one of operating mode of an appliance in which the appliances are not performing their primary task. In this paper a zero leakage power saving system is introduced which will saves the power when only leakage power is associated with the appliances. The appliances will be physically disconnected from mains supply whenever device remains in standby mode for some specific time. The system has three modes of operations - compulsory ON mode, compulsory OFF mode and Intelligent mode. In compulsory ON mode all the appliances will perfume their primary function, in compulsory OFF mode all the appliances will be detached from the mains supply and in intelligent mode the PIR sensors senses the motion and accordingly the electrical appliances will be turned on or off as per requirement. In this way the intelligent mode will saves the energy by making the standby power equal to zero and if the standby power get reduced then the total power consumption also get reduced and it reduces our electricity bill too.

Design of an Aperture-Coupled Frequency-Reconfigurable Microstrip Stacked Array Antenna for LTE and WiMAX Applications

The aim of this paper is to design a novel structure of a frequency-reconfigurable microstrip array antenna by using a combination of aperture-coupled and the stacked patch technology. The four sets of two different aperture slot shapes (I-shaped and H-shaped) are printed on the ground and are functional to transfer the wave and the signal to the selected radiating layers. Both aperture slot positions are based on the bottom patches (layer 2) and top patches (layer 1), respectively. To achieve the frequency reconfigurability, four PIN diode switches are integrated on the feed line layer positioned between both aperture slots on the ground. The activation of the selected patches will determine the current operating frequency of the proposed antenna. A 2.6 GHz or 3.5 GHz frequency is achieved by switching all the PIN diode switches to ON or OFF mode synchronously. The advantage of the proposed antenna is that it can minimize the usage of the antenna’s surface area, with different size of the patch having different operating frequencies, sorted in different layer. The measured results of the return losses, radiation patterns, and the practical indoor propagation measurement achieved good agreement with the simulated results.

A Coplanar Waveguide Fed Rectangular Reconfigurable Patch Antenna with Switchable Strips for Polarization Diversity

A compact single feed rectangular patch antenna with reconfigurable circular polarization has been proposed in this paper. The basic antenna structure is a rectangular patch of dimensions 10 mm x 15 mm printed on a thin FR4 substrate of thickness 3 mm. Two rectangular strips are connected through switches at sideways of the main patch to get polarization diversity. The polarization of the proposed antenna can be reconfigured between left hand circular polarization (LHCP) and right hand circular polarization (RHCP) by the current path, which is changed by operating the switches in ON and OFF modes. The antenna is designed and simulated using IE3D MoM based electromagnetic simulator. The simulated results show good return loss, radiation pattern, axial ratio and acceptable gain at the operating frequency. The antenna has around 15 % effective impedance bandwidth over 4.0 GHz - 4.8 GHz frequency band at a maximum gain of 3.0 dBi with polarization diversity. Defence Science Journal, Vol. 64, No. 1, January 2014, DOI:10.14429/dsj.64.4807

APERTURE-COUPLED FREQUENCY-RECONFIGURABLE STACKED PATCH MICROSTRIP ANTENNA (FRSPMA) INTEGRATED WITH PIN DIODE SWITCH

In this paper, a new Frequency-Reconflgurable Stacked Patch Microstrip Antenna (FRSPMA) with a new coupling method applied in an aperture-coupled technique controlled by the switching circuit is presented. This antenna uses a combination of aperture- coupled technique and stacked patch in order for the radiating elements to increase the bandwidth. Two shapes (I-shape and H-shape) and sizes of aperture slots are etched onto the ground with a purpose to couple the energy between feedline and stacked patch. One PIN diode switch is integrated in the feed network to control the length of the feedline. A variation of the feedline length controls the selected aperture slots to be active. The waves from the selected activated aperture slots will radiate to particular radiating patch (top or bottom patch) and achieve the frequency reconflgurability. When the switch is in ON mode, the antenna has a capability to conflgure its operating frequency at 2.6GHz and at 3.5GHz during the OFF mode. Besides that, the air gap is used to improve and avoid any coupling problem between the aperture slots and both of the two patches. Improper alignment between the aperture slots and patches will interfere waves radiating from aperture slots to the particular patch. In addition, the proposed antenna produces a high gain of more than 5dB during ON or OFF modes, respectively. The simulated results are compared with measured results.

Reconfigurable Microstrip Patch Antenna using MEMS Technology

This project proposes the design of a Reconfigurable Micro Strip Patch Antenna Using MEMS Technology A Reconfigurable Microstrip patch antenna of operating frequency in the range of 5-8 GHz(C- Band), for the application of wireless communication has been designed. The term Reconfigurability refers that it adaptively changes its characteristics. A MEMS-based switch is inserted in the patch to control its configuration. Patch antenna using switchable slots shows different resonant features with different states (ON &OFF) of the switch. When the switch is in the OFF mode, the electric currents on the patch have to flow around the slot, resulting in a relatively long length of the current path. Therefore, the antenna resonates at a low frequency. In contrast, when the switch is in the ON mode, some of the electric currents can go directly through the switch. In this case, the average length of the current path is shorter, so that the antenna has a higher resonant frequency. The antenna was designed and analyzed using ANSOFT HFSS. Keywords - Reconfigurable Antenna, Frequency Diversity, Patch Antenna, Switchable Slot

CFD study and experimental validation of trickle bed hydrodynamics under gas, liquid and gas/liquid alternating cyclic operations

Computational fluid dynamics (CFD) simulations of a trickle bed reactor under gas, liquid, and gas/liquid alternating cyclic operations have been performed by using an unsteady multiple-Euler framework by means of the commercial software FLUENT. Electrical capacitance tomography (ECT) imaging was applied to track the liquid holdup waves along the bed and to validate the CFD simulation results. Comprehensive simulations were conducted to examine the effects of reactor geometry meshing (i.e., one, two, or three-dimensional), domain initialization, numerical schemes (i.e., 1st and 2nd order upwind or 3rd order MUSCL), drag forces, constant coefficients of drag force terms (i.e., Ergun constants), gas and liquid properties and particle size. The important outcome of this work was that a one-dimensional multiple-Euler CFD model with first order numerical scheme was sufficient to accurately capture the non-steady state hydrodynamic behavior of trickle bed reactors under different cyclic operation strategies. This indicates that the alignment of flow and mesh practically eliminates (or minimizes) the numerical diffusion. Moreover, application of uniform bed porosity can predict the hydrodynamics parameters under cyclic operations. The model was able to predict accurately the morphological (i.e., the details of rise and falling or breakthrough and tail as well as plateau) characteristics of a liquid wave inside the bed for all the examined cyclic strategies, including base–peak and ON–OFF modes. In addition, simulation results were in excellent consistency with experimental data in terms of both value and behavior (i.e., fluctuations) of overall bed pressure drop. It was found that the liquid–solid drag force is the main cause of wave attenuation along the bed. The performed case studies with the CFD model revealed the significance of different parameters (e.g., Ergun constants, gas and liquid properties, packing size).

TGF-β-Smad3 signaling in emphysema and pulmonary fibrosis: an epigenetic aberration of normal development?

It is well accepted that TGF-β signaling has critical functional roles in lung development, injury, and repair. We showed previously that null mutation of Smad3, a critical node in the TGF-β pathway, protects mice against fibrosis induced by bleomycin. However, more recently we noticed that abnormal alveolarization also occurs in Smad3-deficient mice and that this is followed by progressive emphysema-like alveolar wall destruction mediated by MMP9. We now know that Smad3 cooperates with c-Jun to synergistically regulate a protein deacetylase SIRT1, by binding to an AP-1 site in the SIRT1 promoter. Consistently, Smad3 knockout lung at postnatal day 28 had reduced SIRT1 expression, which in turn resulted in increased histone acetylation at the binding sites of the transcription factors AP-1, NF-κB, and Pea3 on the MMP9 promoter, as well as increased acetylation of NF-κB. Thus, upon TGF-β activation, phosphorylated Smad3 can be translocated into the nucleus with Smad4, whereat Smad3 in turn collaborates with c-Jun to activate SIRT1 transcription. SIRT1 can deacetylate NF-κB at lysine 30, as well as histones adjacent to the transcription factor AP-1, NF-κB, and Pea3 binding sites of the MMP9 promoter, thereby suppressing MMP9 transcription, hence fixing MMP9 in the OFF mode. Conversely, when Smad3 is missing, this regulatory pathway is inactivated so that MMP9 is epigenetically turned ON. We postulate that these developmental epigenetic mechanisms by which Smad3 regulates MMP9 transcription cell autonomously may be important in modulating both emphysema and pulmonary fibrosis and that this could explain why both pathologies can appear within the same lung specimen.

Electronically controlled asymmetric microstrip line coupler underpinned by an hybrid right-/left-handed line

This work presents a microstrip coupler based on an hybrid right-/left-handed (RH/LH) line whose coupling ratio is electronically controlled. After some considerations on the LH line theory, the asymmetric RH/LH coupler is presented focusing on the parameters yielding the coupling ratio and the frequency range. The dependence of the coupling ratio on the number of cells constituting the coupler is highlighted. From these results, a prototype of a coupler with an electronically switched ratio has been developed. The variable coupling ratio is obtained by switching ON or OFF some cells in the structure of the coupler. The isolation of the OFF mode of the electronic switch implemented is carefully studied. Measurements and calculus are presented in order to estimate the isolation factor required to obtain a significant variation of the coupling ratio as well as to illustrate the original behaviour of such couplers. A functional electronically controlled coupler with one switch implemented is finally characterised and its performances are discussed.

Design and CMOS Implementation of a Low Power System-on-Chip Integrated Circuit

A low power 32-bit microcontroller using different kinds of low-power techniques to adapt to the dynamically changing performance demands and power consumption constraints of battery powered applications is designed and tested. Four power domains and six power modes are designed to fulfill low-power targets and meet different functional requirements. Varieties of low power methods such as dynamic voltage and frequency scaling (DVFS), multiple supply voltages (MSV), power gating (PG) and so on are applied. A novel zero steady-state current POR circuit which makes excellent performance in the chip’s OFF mode is also integrated. The SoC occupies 20 mm2 in a 0.18 um, 1.8 V nominal-supply, CMOS process. Test results show that the microcontroller works normally at the frequency of 70MHz and performs well in different power modes. Yet it only consumes 1.67μA leakage current in the OFF mode.

Analysis of bias effects on the total ionizing dose response in a 180 nm technology

The effects of gamma ray irradiation on the shallow trench isolation (STI) leakage current in a 180nm technology are investigated. The radiation response is strongly influenced by the bias modes, gate bias during irradiation, substrate bias during irradiation and operating substrate bias after irradiation. We found that the worst case occurs under the ON bias condition for the ON, OFF and PASS bias mode. A positive gate bias during irradiation significantly enhances the STI leakage current, indicating the electric field influence on the charge buildup process during radiation. Also, a negative substrate bias during irradiation enhances the STI leakage current. However a negative operating substrate bias effectively suppresses the STI leakage current, and can be used to eliminate the leakage current produced by the charge trapped in the deep STI oxide. Appropriate substrate bias should be introduced to alleviate the total ionizing dose (TID) response, and lead to acceptable threshold voltage shift and subthreshold hump effect. Depending on the simulation results, we believe that the electric field distribution in the STI oxide is the key parameter influencing bias effects on the radiation response of transistor.

Efficacy of motor cortex stimulation in the treatment of neuropathic pain: a randomized double-blind trial

In this study the authors used a double-blind protocol to assess the efficacy of motor cortex stimulation (MCS) for treating neuropathic pain. Eleven patients with unilateral neuropathic pain (visual analog scale [VAS] score 8-10) of different origins and topography were selected for MCS. A 20-contact grid was implanted through a craniotomy centered over the motor cortex contralateral to the painful area. The motor cortex strip was identified using neuroimages, somatosensory evoked potentials, acute electrical stimulation, and corticocortical evoked potentials. Subacute therapeutic stimulation trials allowed the authors to determine the most efficient pair of contacts to use for long-term MCS. The grid was replaced with a 4-contact electrode connected to an internalized stimulator. Bipolar stimulation at a 40-Hz frequency, 90-micro sec pulse width, amplitude 2-7 V, and 1 hour in "ON" and 4 hours in "OFF" mode was used. Pain was evaluated using the VAS, Bourhis, and McGill pain scales applied each month for 1 year. At Day 60 or 90, the stimulators were turned to OFF mode for 30 days in a randomized, double-blind fashion. The statistical tool used was the Wilcoxon test. Three patients did not report improvement in the subacute trial and were excluded from long-term MCS; the remaining patients underwent long-term stimulation. Significant improvement of pain was induced by MCS (p < 0.01); this persisted during the follow-up period. Turning stimulation to OFF mode increased pain significantly (p < 0.05). Improvement at 1 year was >or= 40% (40-86%) in all cases. Motor cortex stimulation is an efficient treatment for neuropathic pain, according to an evaluation facilitated by a double-blind maneuver. Subacute stimulation trials are recommended to determine the optimum motor cortex area to be stimulated and to identify nonresponders.

Microwave analysis of MSM photodiodes for time-resolved measurements of RSFQ pulses

This paper deals with the study of metal–semiconductor–metal (MSM) photodetectors used for time-resolved detection of low amplitude picosecond-range signals, such as rapid single flux quantum (RSFQ) pulses (Likharev and Semenov 1991 IEEE Trans. Appl. Supercond. 1 3–27) generated by superconductive electronic circuits. A typical 6 ps wide incoming RSFQ pulse of 200 µV amplitude has been used for the analysis. The photodetector detection behaviour has been studied in the microwave frequency range for different geometrical parameters in the OFF (no optical illumination) and ON modes. It is shown that, with properly chosen geometry, the photoswitches exhibit good transmission of RSFQ pulses in the ON mode while reasonably shorting them in the OFF mode.

Sympathetic control after cardiac resynchronization therapy: responders versus nonresponders

Cardiac resynchronization therapy (CRT) decreases muscle sympathetic nerve activity (MSNA) in patients with severe congestive heart failure (CHF) and cardiac asynchrony. Whether this affects equally patients who clinically respond or not to CRT is unknown. We tested the hypothesis that the favorable effects of CRT on MSNA disappear on CRT interruption only in those who respond to CRT. Twenty-three consecutive CHF patients participated in the study, among whom 16 presented a symptomatic improvement by one or more New York Heart Association (NYHA) functional classes 15 +/- 5 mo after CRT (responders), and seven had not improved after 12 +/- 4 mo of CRT (nonresponders). MSNA and echocardiographic recordings were obtained in random order during atrio-right ventricular pacing (ARV), without stimulation in patients who were not pacemaker dependent (OFF, n = 17), and during atrio-biventricular pacing (BIV). Responders had a longer 6-min walking distance, a lower NYHA class and brain natriuretic peptide levels, and a better quality of life than did nonresponders (all P < 0.05). MSNA increased by 25 +/- 7% in the responders, whereas it remained unchanged in the nonresponders, when shifting from the BIV mode to a nonsynchronous condition (ARV and OFF modes) (P < 0.01). Cardiac output decreased by 0.7 +/- 0.2 l/min in the responders but did not change when shifting from the BIV mode to the nonsynchronous pacing mode in the nonresponders (P < 0.01). In conclusion, reversible sympathoinhibition is a marker of the clinical response to CRT.

5 Effect of gastric electrical stimulation on cerebral blood flow in patients with gastroparesis

Gastric electrical stimulation (GES) of the stomach is an effective treatment of nausea and vomiting in patients with gastroparesis (Gastroenterology 125: 421–28, 2003). However, the mechanism is unclear, as many patients show resolution of nausea and vomiting yet continue to exhibit delayed gastric emptying. This suggests GES may relieve symptoms by activation of a mechanism involving the central nervous system. The purpose of this study was to determine whether GES produces changes in the brain evidenced by alterations in cerebral blood flow on positron emission tomography (PET). Eight patients (6 females, 2 males) ranging in age from 27 to 68 yr were studied. Each patient had profound gastroparesis and had undergone implantation of a GES device from 6 to 57 mo (mean 25) prior. All patients studied had significant improvement in symptoms of nausea, vomiting, and early satiety after implantation of the GES device. PET scans were performed after an overnight fast and with the GES device in the ON mode. Each patient was then given an IV injection 30–40 mCi O15‐water. After PET image data were obtained the GES device was then turned to the OFF mode for 30 min. The O15‐water injection and PET image scanning was then repeated. Respective PET images obtained with the GES device in the ON and OFF modes were then analyzed and compared. PET images were analyzed using SPM2 (Statistical Parametric Mapping), implemented using Matlab 6.5 Prior to statistical analysis all images were realigned to correct motion movements and spatially normalized into the MNI standard template to remove inter‐subject anatomical variability. Spatially normalized images were smoothed using an isotropic Gaussian kernel with 16 mm FWHM to increase the signal‐to‐noise ratio. Statistical comparisons between ON and OFF scans were performed on a voxel‐by‐voxel basis using paired t statistics. Significant voxels were superimposed on a high resolution MRI template provided by SPM2, thus allowing anatomical identification. Significant increases in blood flow during GES were noted in the middle, superior, and inferior gyri, in the middle occipital and middle temporal gyri, and in the amygdala and parahippocampal gyri (P &lt; 0.05 for each locus, respectively). Likewise, significant decreases in blood flow during GES were noted in the pre and post central gyri, in the anterior cingulate gyri, and in the caudate head and putamen (p &lt; 0.05 for each locus, respectively).Conclusions: 1) GES produces significant alterations in cerebral blood flow in gastroparetic patients; 2) central nervous system mechanisms during GES may be responsible for the relief of nausea and vomiting in these patients.