Total Number Of Devices Research Articles

Heterogeneous WEC array optimization using the Hidden Genes Genetic Algorithm

Wave Energy Converters (WEC) are deployed in arrays to improve the overall quality of the delivered power to the grid and reduce the cost of power production by minimizing the cost of design, deployments, mooring, maintenance, and other associated costs. WEC arrays often contain devices of identical dimensions and modes of operation. The devices are deployed in close proximity, usually having destructive inter-device hydrodynamic interactions. However, in this work, we explore optimizing the number of devices in the array and concurrently, the dimensions of the individual devices (heterogeneous) to achieve better performance compared to an array of identical devices (homogeneous) with comparable overall submerged volume. A techno-economic objective function is formulated to measure the performance of the array while accounting for the volume of material used by the arrays. The power from the array is computed using a time-domain array dynamic model and an optimal constrained control. The hydrodynamic coefficients are computed using a semi-analytical method to enable computationally efficient optimization. The Hidden Gene Genetic Algorithm (HGGA) formulation is used in this optimization problem. During the optimization, tags are assigned to genes to determine whether they are active or hidden. An active gene simulates an active WEC device in the heterogeneous array, while the hidden gene results in a reduction in the total number of devices in the array compared with the homogeneous array. The volume of the heterogeneous array is constrained to be close to that of the homogeneous array. These hidden tags do not exclude the associated devices from the optimization process; these devices keep evolving with the active devices as they might become active in subsequent generations. Heterogeneous arrays were found to perform better than homogeneous arrays.

Analysis of the management of ventriculitis cases at a UK neurosurgery centre

SummaryBackgroundVentriculitis is an infection of the ventricular system of the central nervous system associated with neurosurgery and/or indwelling medical devices mainly caused by coagulase-negative staphylococci and increasingly by Gram-negative bacilli and other Gram-positive bacteria. The Infectious Diseases Society of America (IDSA) and the neurosurgery department University Hospital Coventry and Warwickshire (UHCW) have treatment guidelines for ventriculitis which recommend antimicrobials and device removal.MethodsData on ventriculitis cases, their management and outcomes were collected from electronic laboratory and hospital records as well as patients' paper records from 2009 to 2019. Cases included patients with CSF shunts or external ventricular drainage. The management of the cases was then compared to both Infectious Diseases Society of America (IDSA) and UHCW guidelines. The data collected included the causative organisms and the use of inappropriate antimicrobials. The cost of inappropriate antimicrobials was calculated.Results99 patients with microbiologically confirmed ventriculitis were identified. Some cases had multiple devices and the total number of devices was 105.98% of cases had medical device removal as part of their care. Only 50% and 56% of cases had antimicrobial treatment which was compliant with local (UHCW) and IDSA guidelines, respectively. The most frequently inappropriate antimicrobials used were meropenem and linezolid, at an estimated cost of £201,172 over 10 years. The most frequently isolated organisms were coagulase negative staphylococci. Mortality rate was estimated at 14% of cases.ConclusionsWe report the first analysis of the management of ventriculitis cases at UHCW over a 10-year period and demonstrate the importance of antimicrobial stewardship. We also report the local epidemiology of causes of ventriculitis at UHCW which will guide the empirical treatment of ventriculitis at UHCW.

An Energy-Efficient Scheme for IoT Networks

With the advent of the Internet of Things era, "things-things interconnection" has become a new concept, that is, through the informatization and networking of the physical world, the traditionally separated physical world and the information world are interconnected and integrated. Different from the concept of connecting people in the information world in the Internet, the Internet of Things extends its tentacles to all aspects of the physical world. The proposed algorithm considers the periodical uplink data transmission in IEEE 802.11ah LWPAN and a real-time raw settings method is used. The uplink channel resources were divided into Beacon periods after the multiple nodes send data to the access point. First, the access point predicted the next data uploading time during the Beacon period. In the next Beacon period, the total number of devices that will upload data is predicted. Then, the optimal read-and-write parameters were calculated for minimum energy cost and broadcasted such information to all nodes. After this, the data is uploaded according the read-and-write scheduling by all the devices. Simulation results show that the proposed algorithm effectively improved the network state prediction accuracy and dynamically adjusted the configuration parameters which results in improved network energy efficiency in the IoT environment.

On the Impact of Channel Estimation on the Design and Analysis of IRSA Based Systems

Irregular repetition slotted aloha (IRSA) is a distributed grant-free random access protocol where users transmit multiple replicas of their packets to a base station (BS). The BS recovers the packets using successive interference cancellation. In this paper, we first derive channel estimates for IRSA, exploiting the sparsity structure of IRSA transmissions, when non-orthogonal pilots are employed across users to facilitate channel estimation at the BS. Allowing for the use of non-orthogonal pilots is important, as the length of orthogonal pilots scales linearly with the total number of devices, leading to prohibitive overhead as the number of devices increases. Next, we present a novel analysis of the throughput of IRSA under practical channel estimation errors, with the use of multiple antennas at the BS. Finally, we theoretically characterize the asymptotic throughput performance of IRSA using a density evolution based analysis. Simulation results underline the importance of accounting for channel estimation errors in analyzing IRSA, which can even lead to 70% loss in performance in severely interference-limited regimes. We also provide novel insights on the effect of parameters such as pilot length, SNR, number of antennas at the BS, etc, on the system throughput.

Exploring medical device-related pressure injuries in a single intensive care setting: A longitudinal point prevalence study

ObjectivesTo report longitudinal prevalence rates of device-related pressure injuries in critically ill adult patients in the intensive care unit and to explore the patient characteristics associated with the development of device related pressure injuries. Research designA prospective observational design where observations of patients’ skin integrity were conducted on one day each week for 52 weeks. SettingThe study was conducted in the 36-bed intensive care unit of a major metropolitan tertiary referral hospital in Queensland, Australia. The sample included all patients aged 18 years or older admitted to the intensive care unit before midnight on the day preceding the observation, with a medical device in situ. Main outcome measuresThe primary outcome measure was device related pressure injuries identified at the weekly observations and defined as a pressure injury found on the skin or mucous membrane with a history of medical device in use at the location of the injury. Patient demographic and clinical characteristics were recorded. ResultsOver the study period, 11.3% (71/631) of patients developed at least one hospital-acquired DRPI.The most common devices associated with injury were nasogastric/nasojejunal tubes (41%) and endotracheal tubes (27%). Significant predictors of device related pressure injuries were the total number of devices (OR 1.230, 95% CI 1.09–1.38, p < 0.001), the length of time in the ICU (OR 1.05, 95% CI 1.02–1.09, p = 0.003), male sex, (OR 2.099, 95% CI 1.18–3.7, p = 0.012), and increased severity of illness score on admission (OR 1.044, 95% CI 1.01–1.09, p = 0.013). ConclusionDevice related pressure injuries are an all-too-common iatrogenic problem for this vulnerable patient cohort.

An Energy-Efficient Scheme for IoT Networks

With the advent of the Internet of Things era, things-things interconnection has become a new concept, that is, through the informatization and networking of the physical world, the traditionally separated physical world and the information world are interconnected and integrated. Different from the concept of connecting people in the information world in the Internet, the Internet of Things extends its tentacles to all aspects of the physical world. The proposed algorithm considers the periodical uplink data transmission in IEEE 802.11ah LWPAN and a real-time raw settings method is used. The uplink channel resources were divided into Beacon periods after the multiple nodes send data to the access point. First, the access point predicted the next data uploading time during the Beacon period. In the next Beacon period, the total number of devices that will upload data is predicted. Then, the optimal read-and-write parameters were calculated for minimum energy cost and broadcasted such information to all nodes. After this, the data is uploaded according the read-and-write scheduling by all the devices. Simulation results show that the proposed algorithm effectively improved the network state prediction accuracy and dynamically adjusted the configuration parameters which results in improved network energy efficiency in the IoT environment.

Performance analysis of smart grid dynamic HAN over Rician fading channel

In smart grid (SG) communications, the home area network (HAN) plays a vital role in managing data transmission among communicating devices through a smart meter (SM). Rician fading distribution closely replicates an indoor communication channel in SG HAN system. Thus, channel link is modeled as a Rician fading channel in this paper and Multi‐user selection scheme is employed in SM. Further, a closed‐form expression for average bit error probability (ABEP) performance of indoor dynamic HANs with communicating devices using phase‐shift keying (PSK) modulation is derived and analyzed the effect of traffic intensity, the total number of devices and Rician factor for the considered system. The expression for average channel capacity (ACC) of the SG HAN system is also derived and analyzed by varying the parameters of interest.

Bat echolocation-based algorithm for device discovery in D2D communication

Proximal device discovery is an essential initial phase in the installment of a device-to-device communication system in cellular networks. Therefore, an efficient device discovery scheme must be proposed with characteristics of minimum latency, discover maximum devices, and energy-efficient discovery in dense areas. In this paper, a bat echolocation-based algorithm derived from the bat algorithm is proposed and analyzed to fulfill the requirement of a proximal device discovery procedure for the cellular networks. The algorithm is applied to multiple hops and cluster devices when they are in a poor coverage zone. In this proposed algorithm, devices are not required to have prior knowledge of proximal devices, nor device synchronization is needed. It allows devices to start discovering instantly at any time and terminate the proximal device discovery session on completion of the discovery of the required proximal devices. Finally, device feedback is utilized to discover the hop devices in the clusters and analyze proximal discovery in a multi-hop setting. Along with this, a random device mobility pattern is defined based on human movement, and the device discovery algorithm is applied. The device discovery probability is calculated based on the contact duration and meeting time of the devices. We set up an upper bound less than 10 ms in long-term evolution of running time of the bat echolocation-based algorithm; this upper bound signifies the maximum degree of device discovery (more than 75% of the system) and the total number of devices. The outcomes thus imply that the proposed bat echolocation-based algorithm upper bound is better than 10 ms.

Meta-analysis of Intraprocedural Comparative Effectiveness of Vascular Plugs Vs Coils in Proximal Splenic Artery Embolization and Associated Patient Radiation Exposure

PurposeTo compare vascular plugs to coil embolization of the proximal splenic artery and evaluate differences in radiation exposure to the patients. MethodsAn electronic literature search was performed for relevant studies from January 2000 to July 2018 that compared the efficacy of vascular plugs vs coils in splenic artery embolization. Only studies that investigated coil or vascular plug use, without combination with other embolic agents, were included. Meta-analysis was performed using a fixed effects model approach with the inverse variance-weighted average method to determine pooled differences in time to vessel occlusion, procedure time, fluoroscopy time, total number of devices used, and radiation exposure. Heterogeneity was assessed using the I square statistic. Pooled outcomes were compared, and quality assessments were evaluated using the Newcastle Ottawa Scale. ResultsEight studies met inclusion criteria. 81 patients were embolized with vascular plugs and 52 patients with coils only. The most common indication for splenic artery embolization was trauma. Time to vessel occlusion was shorter in the vascular plug group by 7.11 minutes (P = 0.003). Fluoroscopy time was shorter by 13.82 minutes in the vascular plug cohort, and these patients received less radiation (−439 mGy) compared to the coil group (P = 0.006 and P = 0.02, respectively). The number of devices was significantly fewer in the vascular plug group (−3.54; P < 0.001). Procedure time was not statistically significant. ConclusionOur data supports the vascular plug is superior to coils for embolization of the proximal splenic artery with respect to occlusion time, fluoroscopy time, patient radiation exposure, and number occlusive devices used.

Determinants in the number of staff in hospitals’ maintenance departments: a multivariate regression analysis approach

To date, there are no broadly accepted or accurate models to determine appropriate staffing [levels] for clinical engineering departments (CEDs). The purpose of this study is to determine what the determinants of the staffing levels are (total number of full time equivalents (FTEs)) in CEDs in healthcare organisations. In doing so, we used a cross-sectional exploratory approach by using a multivariate regression model over a secondary source of data information from the AAMI Benchmarking Solutions—Healthcare Technology Management database. Two hundred and one healthcare organisations were included in our study. Our study revealed that on average, there are almost 14 biomedical technicians (BMETs) per clinical engineer and one FTE per 1083.72 devices (SD 545.69). The results of this study also revealed that the total number of devices and the total technology management hours devoted to these devices positively affects the number of FTEs in a CED, whereas the hospital complexity, measured by healthcare organisation patient discharges matters inversely. The most important factor that matters in the number of FTEs in CEDs was the total technology management hours devoted to devices. A value of explained variance (i.e. R2) of 85% was obtained, indicating the strong power of the prediction accuracy of our multivariate regression model.

On a Cognitive Radio Network's Random Access Game With a Poisson Number of Secondary Users

In this letter a random access algorithm based on game theory for cognitive radio networks with random number of secondary users is investigated. The scenario examines a non-cooperative game in which all the players are unaware of the total number of devices participating (population uncertainty). We proposed a scheme where failed attempts to transmit (collisions) are penalized and, consequently, the optimum penalization in mixed strategies is calculated. Furthermore, an analytical approximation for the corresponding Pareto fronts which maximizes the throughput of individual secondary users is obtained. Finally, the impact that the presence of primary users have on the optimal access strategy is assessed.

Performance Analysis of Multiuser Selection Scheme in Dynamic Home Area Networks for Smart Grid Communications

In this paper, multiuser selection scheme is employed in dynamic home area networks (HANs) for smart grid communications, to reduce the effects of fading at the receiver part of smart meter. The performance of multiuser selection scheme is evaluated in two cases: in the absence of interference and in the presence of multiuser interference (MUI). In the former case, the closed-form capacity outage probability as well as the numerical values of the bit error rate (BER) are obtained via the probability density function (PDF) of signal to noise ratio (SNR) that is derived from the amplitude distribution property of the classic indoor Saleh-Valenzuela (S-V) channel. In the latter case, the multiuser interference cancellation coefficient as a random variable is added for the calculation of signal to interference noise ratio (SINR). In addition, due to free space path loss and log-normal shadowing, the sum of MUI is treated as another log-normal-distributed random variable by exploiting central limit theorem. Numerical results show that the performance of multiuser selection scheme in HANs of smart grid is due to several factors, i.e., total number of devices in HANs, traffic intensity, modulation scheme, and multiuser interference cancellation coefficient, etc.

Inside AAMI

The U.S. Food and Drug Administration (FDA) has formally recognized the AAMI version of an international standard on medical electrical equipment.The recognition of ANSI/AAMI ES60601-1:2005—Medical electrical equipment, Part 1: General requirements for basic safety and essential performance and other collateral standards—comes as welcome news to the medical technology community.The standard—which is the U.S. adoption of IEC 60601-1/Ed.3:2006—contains national deviations needed to comply with the National Electrical Safety Code, says Charles Sidebottom, director of corporate standards for Minneapolis-based Medtronic and secretary of IEC/Subcommittee 62A, which developed the IEC standard.The third edition of IEC 60601-1 has been recognized and harmonized in Europe for several years. The AAMI Electrical Safety Committee, which developed the U.S. adoption, is working to harmonize it with NFPA 99, the standard from the National Fire Protection Association (NFPA) on healthcare facilities, says Mike Schmidt, cochairman of the committee.AAMI's Benchmarking Solution now includes more detailed questions on a department's device inventory and associated costs.Launched last year, AAMI's Benchmarking Solution helps clinical engineering departments measure their practices, policies, and procedures against others, and monitor their progress through the year. The online tool can be used to measure staffing, budgeting, inspections, and other issues.Subscribers answer a series of questions about their department and operation; and they can then see how their facility compares to others. The clinical engineering experts who drafted the questions made the enhancements in response to subscriber requests.For example, the experts broke down two questions about the total number of devices in an inventory into four categories: imaging, laboratory, general biomedical equipment, and non-patient care equipment.This will help subscribers compare certain types of equipment at other facilities. For more information about AAMI's Benchmarking Solution, visit www.aami.org/abs.

Improved Subset Difference Method with Ternary Tree

This paper proposes a ternary subset difference method (SD method) that is resistant to coalition attacks. In order to realize a secure ternary SD method, we design a new cover-finding algorithm, label assignment algorithm and encryption algorithm. These algorithms are required to revoke one or two subtrees simultaneously while maintaining resistance against coalition attacks. We realize this two-way revocation mechanism by creatively using labels and hashed labels. Then, we evaluate the efficiency and security of the ternary SD method. We show that the number of labels on each client device can be reduced by about 20.4 percent. The simulation results show that the proposed scheme reduces the average header length by up to 15.0 percent in case where the total number of devices is 65, 536. On the other hand, the computational cost imposed on a client device stays within O(log n). Finally, we prove that the ternary SD method is secure against coalition attacks.

Entropy as a measure of diversity in an inventory of medical devices

Quantitative techniques for the measurement of species diversity have been developed in ecological studies. One such technique, based on an entropy measurement, has been applied to the assessment of medical device diversity in large inventories of medical equipment. Using this technique it is possible to identify trends which are not apparent from simple considerations of the total number of devices, or the number of device types. Objective measurements of this type can be used to monitor the progress of planned equipment replacement programmes.

A half-adder (HA) and a full-adder (FA) combining single-electron transistors (SETs) with MOSFETs

A half-adder (HA) and a full-adder (FA), using single-electron metal–oxide–semiconductor field-effect transistors (SE-MOSFET) hybrid circuits, are proposed. The proposed HA consists of three single-electron transistors (SETs), two enhancement-mode NMOSFETs and two depletion-mode NMOSFETs, and the proposed FA consists of four SETs, four enhancement-mode NMOSFETs, one enhancement-mode PMOSFET and three depletion-mode NMOSFETs. The total number of devices in the HA and the FA are 7 and 12, respectively. Compared with the conventional CMOS mirror FA with the 90 nm technology, the proposed FA can be constructed with 0.43 of devices and can operate with 5.6 of worst-case delay, 1/10.3 of average power consumption and 0.55 of power-delay product. The proposed HA and FA can be operated as a half-subtractor (HS) and a full-subtractor (FS) in the case when the levels of the control gates in the HA and the FA are suitably determined. The basic operations of the proposed HA, HS, FA and FS have been successfully confirmed through SPICE circuit simulation based on the physical device model of the SET.

The prevalence of women with breast implants in the United States—1989

Most estimates of the number of women with breast implants appear to be extrapolations of industry or clinical data. While both provide valuable information, the former about the total number of devices ever produced or sold and the latter about the cumulative number of surgeries performed, neither can be used to directly estimate the prevalence of women with silicone gel or saline implants. In 1989, Market Facts, Inc., conducted a mail survey of 40,000 households chosen as representative of the population of the United States and received responses from 70.7%. Overall, the prevalence was 8.08 per 1,000 women with about 60% of the devices reportedly implanted for cosmetic reasons. The procedure was more common among Whites of the higher socio-economic classes. Based upon the results of this survey, the total number of US women in 1989 with breast implants was estimated to be 815,700 (95% confidence interval: 715,757–924,729).

Yield analysis of multilayer optical coatings

Yield is defined as the ratio of the number of devices that satisfy a particular technical specification to the total number of devices produced. For coated optical devices, random layer thickness variations decrease the yield. Variations in refractive index can also affect yields, but in this work we assume that changes in index are not as important as changes in thickness. A graphic method of yield analysis for optical coatings is presented. This method probes the sensitivity of the device performance against thickness variations and translates it into yield figures. Five examples of this analysis are provided including spectral and nonspectral applications.