Search results for " frequency"
showing 10 items of 1398 documents
ZigBee networks performance under WLAN 802.11b/g interference
2009
ZigBee is a standard protocol suite for low rate wireless personal area networks (LR-WPANs) and has been widely utilized in various fields. Since both ZigBee and WLAN (802.11b/g) operate in the 2.4GHz unlicensed industrial scientific medical (ISM) frequency band, mutual interference is likely to exist and cause signal degradation. In this paper, an interference analysis model is suggested to obtain an estimate of Packet Error Rate (PER) of a ZigBee network. A ZigBee evaluation kit, AVR RZ200, was implemented for measurement of Packet Loss Ratio (PLR). The measured PLR matches the estimated PER, with varied distances and different center frequency offsets of different channels.
HLA genotype in patients with acquired haemophilia A
2010
Acquired haemophilia A (AH) is a rare bleeding disorder caused by an auto-antibody to coagulation factor VIII. It is associated with various autoimmune diseases, pregnancy, cancer or drug ingestion; however, in 50% of patients, no underlying disorder is found. In the present study, we investigated the association of HLA class I (A, B and Cw) and class II (DRB1 and DQB1) alleles with AH in a cohort of 57 patients. While no association with any class I allele was detected, a significantly higher frequency of DRB1*16 [odds ratio (OR) 10.2, 95%CI: 5.32-19.57, P < 0.0001] and DQB1*0502 (OR 2.2, 95%CI: 1.12-4.54, P < 0.05) was observed. In contrast, the frequency of DRB1*15 and DQB1*0602 alleles …
Demo - Dynamic Adaptations of WiFi Channel Widths Without TX/RX Coordination
2017
Most modern standards for wireless communications support physical layer adaptations, in terms of dynamic selection of channel central frequency, transmission power, modulation format, etc., in order to increase link robustness under time-varying propagation and interference conditions. In this demo, we demonstrate that another powerful solution for extending physical layer flexibility in OFDM-based technologies is the dynamic adaptation of the channel width. Although some standards already define the possibility of utilizing multiple channel widths (e.g. 20MHz, 10MHz, 5MHz for IEEE 802.11a standards), such an utilization is limited to a static configuration of a value defined during the ne…
Side Effects of Ambient Noise Immunity Techniques on Outdoor IEEE 802.11 Deployments
2008
A very common conclusion of many experimental studies about IEEE 802.11 outdoor network deployments is that their poor performance results derive from the unfavorable interference and multi-path signals in which the WLAN-cards are required to operate. Goal of this paper is to show that this condition does not always hold, and unexpected and inaccurated PHY layer implementations can be a primary cause of packet losses. With the support of extensive measurement campaigns led in our campus, we provide the performance evidence that IEEE 802.11 outdoor performance impairments are strongly affected by proprietary interference mitigation techniques that adaptively adjust the WLAN-card receiver sen…
Sensitivity and Specificity of Stability Criteria for Immediately Loaded Splinted Maxillary Implants
2014
Background To assess the suitability of dental implants for immediate loading, primary stability is usually evaluated intraoperatively. Purpose This retrospective study aimed to assess the suitability of three stability parameters – namely, insertion torque (IT), implant stability quotient (ISQ; measured by resonance frequency analysis), and Periotest (PT) values – as potential predictors for the risk of nonosseointegration of immediately loaded splinted implants. The stability parameters were routinely collected under immediate loading. Materials and Methods Nineteen patients with 11 edentulous and 8 partially edentulous maxillae were treated with 105 dental implants, which were immediatel…
Updated secondary implant stability data of two dental implant systems. A retrospective cohort study
2017
Background At present, updated secondary implant stability data generated by actual versions of resonance frequency analysis (RFA) and mobility measurement (MM) electronic devices of 2 different implant systems with actual manufactured surfaces seem to lack and/or are incomplete. Material and Methods Secondary implant stability data based on both RFA and MM measurements were collected and analyzed from 44 formerly treated patients (24 f, 20 m) that received either Ankylos Cellplus (Ø3.5mm) (A) (n=36) or Straumann regular neck SLA tissue level (Ø4.1mm) (S) (n=37) implants in posterior positions of both jawbones (total number= 72). These results were interpretated in view of formerly publishe…
Frequency Regulation of Hybrid Power System by Optimized Adaptive Fuzzy PID Controller
2020
In this study, an adaptive fuzzy PID (AFPID) regulator has been proposed for frequency control of hybrid power system. For controller parameter optimization, an upgraded Whale Optimization Algorithm (WOA) has been employed. In the proposed Upgraded WOA (UWOA) technique, a cosine function is incorporated in the original WOA for determining control parameter to manage the position of whales throughout optimization procedure. Furthermore, scaling factors are employed in original WOA to adjust the travel of whales in search procedure. Proposed UWOA technique is employed to design an AFPID controller for frequency regulation of a hybrid power system It is demonstrated that UWOA technique out per…
Polymer-doped UHF RFID tag for wireless-sensing of humidity
2012
Passive UHF RFID tags, beside item labelling, are also able to exploit capability of sensing the physical state of the tagged object as well as of the surrounding environment. Here a family of polymer-doped tags are proposed and fully characterized for the detection of ambient humidity. A sensitive chemical species based on PEDOT:PSS is used to dope a properly shaped slot carved into a folded-like patch tag. The communication and sensing capabilities of the radio-sensor are investigated by means of simulation and measurements showing how to control and balance above opposite requirements by dosing the quantity of sensitive material. The device could have interesting application in the asses…
Underdamped soft phonon in orthorhombic BaTiO3
1990
Abstract Raman scattering measurements are reported in orthorhombic phase and through the orthorhombic-rhombohedral transition of BaTiO3. Spectra reveal the presence of an underdamped low frequency phonon which slightly softens with decreasing temperature and abruptly stiffens at the transition to the rhombohedral phase. Results are discussed in comparison with isomorphous KNbO3 and tetragonal BaTiO3 and are interpreted as due to a dominant displacive mechanism.
Effect of physical aging on the low-frequency vibrational density of states of a glassy polymer
2003
The effects of the physical aging on the vibrational density of states (VDOS) of a polymeric glass is studied. The VDOS of a poly(methyl methacrylate) glass at low-energy (<15 meV), was determined from inelastic neutron scattering at low-temperature for two different physical thermodynamical states. One sample was annealed during a long time at temperature lower than Tg, and another was quenched from a temperature higher than Tg. It was found that the VDOS around the boson peak, relatively to the one at higher energy, decreases with the annealing at lower temperature than Tg, i.e., with the physical aging.