Count Loss Research Articles

Single-Phase AC–DC–AC Three-Level Three-Leg Converter With Reduced Switch Count

This paper presents a new single-phase ac–dc–ac three-level three-leg converter composed of three coupled-inductors and six active switches. The system model, operation principles, and a control strategy are presented and discussed. Additionally, a space-vector pulsewidth modulation technique is developed to double the effective frequency of the grid and load voltages and to reduce the switching losses. The proposed converter is compared to other similar converters in terms of switch count, harmonic distortion, and power losses. The results show that the proposed topology has improved power quality and uses fewer switches and gate drive circuits. These characteristics can potentially reduce the costs and the complexity of the system. In addition, the proposed converter eliminates the requirement for dead time to prevent short circuit of the dc-link. In order to validate the theoretical analysis, simulated and experimental results are presented and discussed.

Efficiency of marination liquids prepared with koruk (Vitis vinifera L.) on safety and some quality attributes of poultry meat

In this study, the effects of marination liquids (ML) prepared with koruk juice on safety and quality of poultry meat were investigated. Meat samples inoculated with Salmonella Typhimurium (≅ 6 log CFU/g) were marinated with different concentrations of koruk juice at 4 °C for 1, 2 and 18 h. As a result of the process, the counts of S. Typhimurium on meat samples were reduced in the range of 0.113–3.476 log CFU/g. The most effective treatment in reducing the counts of S. Typhimurium was achieved by marination with ML1 (100% koruk juice) for 18 h. TMAB counts of uninoculated meat samples were determined under detection limits after marination with ML1 for all marination times. When the concentration of koruk juice were increased in ML, TMAB count, pH value and cooking loss of marinated meat samples were decreased. After marination, L∗, a∗ and b∗ values of meat samples were also increased. The samples marinated with ML3 (50% koruk juice + 50% water) and C1 (100% olive oil) for 18 h were the most favored samples in terms of general appreciation. The present results indicated that koruk juice could be used as alternative ML to improve the safety and quality of poultry meat.

Performance evaluation of the 5‐Ring GE Discovery MI PET/CT system using the national electrical manufacturers association NU 2‐2012 Standard

PET performance was evaluated at three different institutions. Spatial resolution, sensitivity, counting rate performance, accuracy, and image quality were measured in accordance with National Electrical Manufacturers Association NU 2-2012 standards. The mean energy resolution, mean timing resolution, and PET/CT subsystem alignment were also measured. Phantoms were used to determine the effects of varying acquisition time and reconstruction parameters on image quality. Retrospective patient scans were reconstructed with various scan durations to evaluate the impact on image quality. Results from all three institutions were similar. Radial/tangential/axial full width at half maximum spatial resolution measurements using the filtered back projection algorithm were 4.3/4.3/5.0mm, 5.5/4.6/6.5mm, and 7.4/5.0/6.6mm at 1, 10, and 20cm from the center of the FOV, respectively. Measured sensitivity at the center of the FOV (20.84cps/kBq) was significantly higher than systems with reduced axial FOV. The peak noise-equivalent counting rate was 266.3kcps at 20.8kBq/ml, with a corresponding scatter fraction of 40.2%. The correction accuracy for count losses up to the peak noise-equivalent counting rate was 3.6%. For the 10-, 13-, 17-, 22-, 28-, and 37-mm spheres, contrast recoveries in the image quality phantom were measured to be 46.2%, 54.3%, 66.1%, 71.1%, 85.3%, and 89.3%, respectively. The mean energy and timing resolution were 9.55% and 381.7ps, respectively. Phantom and patient images demonstrated excellent image quality, even at short acquisition times or low injected activity. Compared to other PET/CT models, the extended axial FOV improved the overall PET performance of the 5-ring GE Discovery MI scanner. This system offers the potential to reduce scan times or injected activities through increased sensitivity.

Pulse pileup analysis for a double-sided silicon strip detector using variable pulse shapes.

Due to pulse pileup, photon counting detectors (PCDs) suffer from count loss and energy distortion when operating in high count rate environments. In this paper, we studied the pulse pileup of a double-sided silicon strip detector (DSSSD) to evaluate its potential application in a mammography system. We analyzed the pulse pileup using pulses of varied shapes, where the shape of the pulse depends on the location of photon interaction within the detector. To obtain the shaped pulses, first, transient currents for photons interacting at different locations were simulated using a Technology Computer-Aided Design (TCAD) software. Next, the currents were shaped by a CR-RC2 shaping circuit, calculated using Simulink. After obtaining these pulses, both the different orders of pileup and the energy spectrum were calculated by taking into account the following two factors: 1) spatial distribution of photon interactions within the detector, and 2) time interval distribution between successive photons under a given photon flux. We found that for a DSSSD with thickness of 300 μm, pitch of 25 μm and strip length of 1 cm, under a bias voltage of 50 V, the variable pulse shape model predicts the fraction free of pileup can be > 90 % under a photon flux of 3.75 Mcps/mm2. The double-sided silicon-strip detector is a promising candidate for digital mammography applications.

Comparison of Noise Equivalent Count Rates (NECRs) for the PET Systems With Different Ring Diameter and Electronics

Because the sensitivity of positron emission tomography (PET) system increases in proportion to the inverse of the diameter of the detector ring, brain PET systems are being planned and developed. However, count losses due to the dead-time of the detector blocks increases as the ring diameter decreases. Since the count losses decrease the noise equivalent count rate (NECR) of the system, the NECR of brain PET system may be lower than that of a whole-body PET system in clinical dose range. In this paper, we compared the NECRs of brain PET systems with that of a whole-body PET system using a Monte Carlo simulation. We simulated the PET system for a 27-cm-diameter detector ring, a 54-cm-diameter detector ring, and an 89-cm-diameter detector ring and evaluated the NECRs. In the clinical dose range, the NECR of the small-diameter brain PET system was lower than those of the whole-body PET system unless the electronics was advanced. We conclude that the small-diameter brain PET system with conventional electronics has not so much advantage except for the lower cost and the higher spatial resolution. However, advanced electronics can reduce degradation of NECR, so the small-diameter brain PET system with advanced electronics will be useful for clinical studies.

PRELIMINARY TECHNICAL DISCUSSION ON A NEW RADON AND ITS PROGENY CONTINUOUS MONITOR USING TWO-FILTER METHOD.

Focusing on the scalability of Two-Filter Method, we started to develop a monitor for the concentration of radon and its progeny. In this study, we investigated the influence of a high-humidity environment on measuring radon concentration, and the influence of the decay chamber of the monitor on the measurement. In the high-humidity test, the conversion factor of (Bqm-3)/(cpm) tends to raise with increasing humidity. On the measurement of radon progeny, existence of the decay chamber of the monitor makes measurement sensitivity lower under environments of little aerosols. Radon concentration measurement by the developed monitor could be influenced by environmental humidity, and that counting loss could occur due to deposition of radon progeny inside of the decay chamber. Correction relating these would be needed based on the data of calibration tests.

Multiple Facets of the Poisson Distribution Applicable to Health Physics Measurements.

This paper discusses several ways to view the standard Poisson distribution as applied to health physics scaler counts. The intent is not so much to present calculational details but rather to present some underlying concepts. Examples are provided that illustrate the various concepts for several types of specific measurements. The concepts presented involve purely Poisson-based contributions to variance; extra-Poisson variance is presently ignored, and any counting system would be presumed to function properly and without counting loss.

Immunological Efficacy of Tenofovir Disproxil Fumarate-Containing Regimens in Patients with HIV-HBV Co-Infection: A Meta-Analysis

Background: Hepatitis B virus (HBV) co-infection is common in HIV patients. HIV infection modifies the natural course of HBV infection, leading to a faster progression of liver-related morbidity and mortality than for HBV mono-infection. This systematic review and meta-analysis evaluates current clinical evidence for the use of oral TDF-based treatments in patients with HIV-HBV co-infection. Methods: We performed a comprehensive literature search in PubMed and Web of Science. Supplementary searches were conducted in Google Scholar and Clinicaltrials.gov. We conducted a random-effects meta-analysis, using the event rate (ER) to estimate the incidence of HBV seroconversion. Subgroup meta-analysis was performed to assess the moderate effects of demographic and disease-related variables on HBsAg loss. This review is registered in the PROSPERO database (CRD42018092379). Findings: We included 11 studies in the review. The immunological effects of oral Tenofovir Disproxil Fumarate (TDF)-based PrEP treatment in patients with HIV-HBV co-infection were 0.249 (95% CI: 0.155-0.376, p<0.001) for HBeAg loss, 0.237 (95% CI 0.145-0.362, p<0.001) for HBeAg conversion, 0.073 (95% CI 0.044-0.119, p<0.001) for HBsAg loss and 0.055 (95% CI 0.02-0.142, p<0.001) for HBsAg conversion, respectively. The factors associated with HBsAg loss were baseline HBV viral load, participant location and history of exposure to LAM/FTC (all p<0.05). A trend toward a negative relationship baseline CD4+ T-cell count and HBsAg loss was observed (p=0.078). Interpretation: Oral TDF-containing regimens are effective for seroconversion in patients with HIV-HBV co-infection. Well-designed prospective cohort studies and large randomized clinical trials (RCTs) are now required to investigate potential predictors and biological markers of HBV remission in patients with HIV-HBV co-infection. Funding Statement: This work was supported by the National 13th 287 Five-Year Grand Program on Key Infectious Disease Control (2018ZX10301407-005-001 to T.Y., 2017ZX10202102-005-003 to B.S., 2017ZX10202101-004-001 to T.Z.), the National Natural Science Foundation of China (NSFC, 81772165 to B.S., 81571973 to H.W.), the NSFC-NIH Biomedical collaborative research program (81761128001 to H.W.), the Beijing Municipal of Science and Technology Major Project (D161100000416003 to H.W.), the Funding for Chinese overseas talents returning to China in 2016 (to B.S.), the Beijing Key Laboratory for HIV/AIDS Research (BZ0089). Declaration of Interests: The authors declare that they have no conflicts of interest. Ethics Approval Statement: This review is registered in the PROSPERO database CRD42018092379).

New topology of a switched‐capacitor‐based multilevel inverter with a single DC power supply

The utilisation and importance of multilevel inverters, as one of the key component of new electrical systems, are ever-increasing. As a result, many works and evolutions have been carried out, which lead to improvements of topologies and control strategies. Newly introduced topologies can generate output voltage with maximum level number, minimum switching components and power supplies. This study introduces a multilevel inverter with minimum number of DC power supply and optimum number of semiconductors based on the switched-capacitor method. One of the best features of the proposed topology is its voltage generation with boost capability without any need for H-bridge. Moreover, the proposed topology has modular extension capability in order to increase the number of output levels. The comparison between the proposed converter and some previous topologies shows that it has better conditions with respect to the used semiconductor count, switches and capacitors losses. The operation and performance of the proposed multilevel converter have been ascertained through simulations and verified experimentally for a single-phase 17-level inverter. All results are illustrated to show the proposed converter's ability in smooth sinusoidal output voltage generation with boosting the input voltage without any transformer.

Attenuation of adverse effects of noise induced hearing loss on adult neurogenesis and memory in rats by intervention with Adenosine A2A receptor agonist

Hearing loss and cognitive decline are commonly associated with aging and morbidity. Present clinical interest lies in whether peripheral hearing loss promotes cognitive decline and if prophylaxis with selective adenosine receptor agonist CGS21680 effectively mitigates the adverse effects. In the current study, male Sprague Dawley rats weighing 200–250 g m were randomly allocated into three groups: Group 1) rats exposed to 100 dB SPL white noise, 2 h a day for 15 consecutive days, 2) rats supplemented with an adenosine receptor agonist, CGS21680 at 100 μg/kg/day prior to noise exposure and 3) unexposed control rats. Baseline hearing and cognition assessed by auditory brainstem response (ABR) and water maze respectively was undertaken for all the groups. Phalloidin stain and synaptic ribbons count in cochlea, and, Ki67, DCX and NeuN in hippocampus were observed by immunohistochemistry. It was inferred that noise exposed rats showed elevated thresholds of ABR and poorer performances in spatial working memory when compared with controls. On the contrary, CGS21680 administered group exhibited improved ABR and cognitive functions with shorter mean latency and path-length to reach the platform, significant reduction in the noise induced loss of synaptic ribbons count and increased number of Ki67 and doublecortin (DCX) positive cells compared to their noise exposed counterparts. Pharmacologic intervention with selective A2A receptor agonist CGS21680 provided adequate protection from noise by effectively maintaining hearing threshold levels, cell viability in cochlea and hippocampus & functional/intact reference memory.

An Improved Classification Analysis on Utility Aware K-Anonymized Dataset

K anonymization is one of the worldwide used approaches to protect the individual records from the privacy leakage attack of Privacy Preserving Data Mining (PPDM) arena. Typically anonymized dataset will impact the effectiveness of data mining results. Anyhow, currently researchers of PPDM progress in driving their efforts in finding out the optimum trade-off between privacy and utility. This work tends in bringing out the optimum classifier from a set of best classifiers of data mining approaches that are capable enough in generating value-added classifying results on utility aware k-anonymized data set. We performed the analytical approach on the data set that are anonymized in sense of accompanying the anonymity utility factors like null values count and transformation pattern loss. The experimentation is done with three widely used classifiers HNB, PART and J48 and these classifiers are analysed with Accuracy, F-measure, and ROC-AUC which are literately proved to be the perfect measures of classification. Our experimental analysis reveals the best classifiers on the utility aware anonymized data sets of Cell oriented Anonymization (CoA), Attribute oriented Anonymization (AoA) and Record oriented Anonymization (RoA).

Model-Based Pileup Events Correction via Kalman-Filter Tunnels

A Kalman-filter-based method is proposed to address challenges in nuclear signal processing, including pileup events and noise cancelation. The state-transition equation is established on the basis of suitable pulse shape models. By regarding the output signal of particle detectors as a measurable variable, the measurement equation is also introduced to correct dynamic processes of the state transition. A linear Kalman filter with $n$ tunnels is constructed to separate pileup events and maintain the original waveforms of pulses. In addition, two terms are defined and addressed for separation operations, namely, Availability , which is used to prepare for upcoming events, and Clearance Mechanism , which is given to remove thumbnail information from the previous events and make occupied tunnels available to subsequent nuclear events. Simulation and field experiments demonstrate that the proposed method can handle critical situations of pulse pileup and minimize count loss and dead time in the X-ray energy spectrum while maintaining the original pulse shapes.

Improved Crowd Counting Method Based on Scale-Adaptive Convolutional Neural Network

Crowd counting is a challenging task due to the influence of various factors, such as scene transformation, complex crowd distribution, uneven illumination, and occlusion. To overcome such problems, scale-adaptive convolutional neural network (SaCNN) used a convolutional neural network to obtain high-quality crowd density map estimation and integrate the density map to get the estimated headcount. To obtain better performance on crowd counting, an improved crowd counting method based on SaCNN was proposed in this paper. The spread parameter, i.e., the standard variance, of geometry-adaptive Gaussian kernel used in SaCNN was optimized to generate a higher quality ground truth density map for training. The absolute count loss with weight 4e-5 was used to jointly optimize with the density map loss to improve the network generalization ability for crowd scenes with few pedestrians. Also, a random cropping method was applied to improve the diversity of training samples to enhance network generalization ability. The experimental results upon ShanghaiTech public dataset showed that the proposed method can obtain more accurate and more robust results on crowd counting than those of SaCNN.

MYH9-related disorders display heterogeneous kidney involvement and outcome.

BackgroundMYH9-related diseases (MYH9-RD) are autosomal dominant disorders caused by mutations of the MYH9 gene encoding the non-muscle myosin heavy chain IIA. They are characterized by congenital thrombocytopenia, giant platelets and leucocyte inclusions. Hearing impairment, pre-senile cataract and nephropathy can also occur. We aimed to evaluate renal involvement and outcome in MYH9-RD patients followed-up by nephrologists.MethodsWe conducted a retrospective multicentre observational study of 13 patients among 9 families with MYH9 mutation diagnosed by genetic testing and immunofluorescence assay referred to nephrologists.ResultsAt initial referral, median age was 30 (range 14–76) years. Median estimated glomerular filtration rate was 66 mL/min/1.73 m2 (0–141) and two patients had already end-stage renal disease (ESRD). Renal presentation associated proteinuria (n = 12), haematuria (n = 6) and hypertension (n = 6). Three patients developed a rapid onset ESRD whereas five others had a relatively stable kidney function over a 3-year median follow-up (1–34). Extra-renal features varied widely, with hearing impairment in six patients, cataract in two and mild liver dysfunction in seven. Thrombocytopenia existed at referral in 11 patients. Time to diagnosis varied from 0 to 29 years (median 3 years). Initial diagnoses such as idiopathic thrombocytopenic purpura (n = 4) and focal segmental glomerulosclerosis (n = 1) led to corticosteroid administration (n = 4), intravenous immunoglobulins (n = 3), cyclophosphamide (n = 1) and splenectomy (n = 1).ConclusionsRenal involvement and outcome in MYH9-RD are heterogeneous. The diagnosis is often delayed and misdiagnoses can lead to unnecessary treatments. MYH9-RD should be considered in any patient with glomerular involvement associated with a low or slightly decreased platelet count and/or hearing loss and liver dysfunction.

Predictors of Response in Patients Receiving CD34-Selected Stem Cell Infusions without Conditioning to Correct Graft Failure Following Allogeneic Stem Cell Transplantation

▪Introduction: Graft failure (GF) is an infrequent but serious complication of following matched related or unrelated donor peripheral blood stem cell transplantation. Although infusion of CD34+-selected stem cells without additional conditioning is currently one strategy to treat this complication, few studies have reported predictors of response.Methods: We report the outcome of consecutive patients identified at two UK transplant centres between 1999 and 2017 who had primary or secondary GF after an allogeneic peripheral blood stem cell transplant and who underwent a CD34+ selected stem cell infusion without further conditioning. GF was confirmed by chimerism, bone marrow examination and exclusion of relapsed disease. Primary GF was defined by failure to ever achieve count recovery in one or more lineages (neutrophils >0.5x109/L, untransfused platelets >20 x109/L and untransfused Hb >8 g/L) post transplantation. Secondary GF was defined by loss of counts after the initial achievement of engraftment. A complete response (CR) was defined as haematological improvement (HI) in all cell lines (Hb>8g/L, platelets > 30x109/L and neutrophils > 1.5x109/L). A partial response (PR) was defined as HI within the first 30 days but not in all cell lineages. Responses were categorized as early (<30 days after infusion) versus late (>30 days); in the latter case, the role of the CD34+ infusion in count recovery was not known.Results: We identified 62 patients with GF, male:female 35:27, with a median age of 43 years (range, 10-66). Fifty-six patients (90%) had had reduced intensity conditioning. Median follow up was 6.4 years. Diagnoses included acute leukemia (n=18), non-Hodgkin's lymphoma (n=18), Hodgkin's Lymphoma (n=7), MDS (n= 6), multiple myeloma (n=3), myelofibrosis (n=2), CLL (n=2), severe aplastic anaemia (n=2), primary immunodeficiency (n=2), CML (n=1) and sickle cell disease (n=1). The original graft source was peripheral blood stem cells from a matched related donor (n=29), matched unrelated donor (n=18) and mismatched unrelated donor (n=15). Twenty-one (34%) patients had primary GF and 41 (66%) had secondary GF. Forty-three patients (69%) had GF in all 3 lineages and 19 patients (31%) had GF in 1 or 2 lineages. The median CD34+ cell dose/kg recipient weight was 3.2 x 106/kg (range, 0.47-14.2 x 106/kg) at a median of 181 days (range, 21-2718 days) following transplant. No response to CD34+ infusion was seen in 15 (24%) patients. Of the remaining 47 patients who responded (76%), 19 patients achieved a CR <30 days, 19 patients had a CR >30 days, 5 had a PR <30 days and 4 had a PR >30 days. Of those who responded, the median number of days required for neutrophil recovery was 29 days (6-1182), platelets recovery was 18 days (5-600) and haemoglobin recovery was 25 days (6-511). In a multivariate analysis, parameters significantly associated with response were CMV serostatus negative for both patient and donor (OR: 20.12, CI 95%= 1.6 - 248) and matched patient/donor sex (OR: 73, CI 95%= 3.3- 1605). Other factors including CD34+ dose, unrelated/related donor, underlying disease, disease risk score, timing of infusion, recipient/donor age, primary or secondary GF and presence or absence of GVHD did not predict for response. Overall survival (OS) for all patients at 1 and 5 years was 70% (95% CI 58-82) and 54% (95% CI 41-68) respectively. OS at 1 and 5 years was 86.4% (95% CI 75-98) and 73.6% (95% CI 54-92) in patients showing a CR versus 66.7% (95% CI 35-98) and 27.8% (95% CI 3-60) in patients with PR (Figure 1). Patients showing no response had poor outcomes with OS of 33.3% (95% CI 9-58) and 22.2% (CI 95% 5-47) at 1 and 5 years. In responding patients, those who initially had GF in 1-2 lineages had 5-year OS of 93.8% (95% CI 82-99) versus GF in 3 lineages who had a 5-year OS of 53% (95% CI 34-88) (Figure 2).Conclusions: This analysis represents the largest report of outcomes in patients who have received a CD34+ selected stem cell infusion without conditioning for GF. Negative donor/recipient CMV serostatus and sex matching predicted response. In responding patients, GF initially affecting <3 lineages was a predictor of better OS at 5 years. New strategies including cytokine or agonist support, or second transplant need to be investigated in partially or non-responding patients. [Display omitted] DisclosuresHough:University College London Hospital's NHS Foundation Trust: Employment.

EARTHQUAKE FORECASTING USING ARTIFICIAL NEURAL NETWORKS

Abstract. Earthquake is one of the most devastating natural calamities that takes thousands of lives and leaves millions more homeless and deprives them of the basic necessities. Earthquake forecasting can minimize the death count and economic loss encountered by the affected region to a great extent. This study presents an earthquake forecasting system by using Artificial Neural Networks (ANN). Two different techniques are used with the first focusing on the accuracy evaluation of multilayer perceptron using different inputs and different set of hyper-parameters. The limitation of earthquake data in the first experiment led us to explore another technique, known as nowcasting of earthquakes. The nowcasting technique determines the current progression of earthquake cycle of higher magnitude earthquakes by taking into account the number of smaller earthquake events in the same region. To implement the nowcasting method, a Long Short Term Memory (LSTM) neural network architecture is considered because such networks are one of the most recent and promising developments in the time-series analysis. Results of different experiments are discussed along with their consequences.

A High-Density Crowd Counting Method Based on Convolutional Feature Fusion

In recent years, the trampling events due to overcrowding have occurred frequently, which leads to the demand for crowd counting under a high-density environment. At present, there are few studies on monitoring crowds in a large-scale crowded environment, while there exists technology drawbacks and a lack of mature systems. Aiming to solve the crowd counting problem with high-density under complex environments, a feature fusion-based deep convolutional neural network method FF-CNN (Feature Fusion of Convolutional Neural Network) was proposed in this paper. The proposed FF-CNN mapped the crowd image to its crowd density map, and then obtained the head count by integration. The geometry adaptive kernels were adopted to generate high-quality density maps which were used as ground truths for network training. The deconvolution technique was used to achieve the fusion of high-level and low-level features to get richer features, and two loss functions, i.e., density map loss and absolute count loss, were used for joint optimization. In order to increase the sample diversity, the original images were cropped with a random cropping method for each iteration. The experimental results of FF-CNN on the ShanghaiTech public dataset showed that the fusion of low-level and high-level features can extract richer features to improve the precision of density map estimation, and further improve the accuracy of crowd counting.

An alternative methodology for high counting-loss corrections in neutron time-of-flight measurements

In counting experiments associated with pulsed sources, a high data collection rate can lead to considerably large counting losses, especially in the case of spallation Time-of-Flight facilities equipped with medium and short flight paths where the research interest is focused on higher neutron energies where counting losses can be quite large due to the higher neutron flux, the more compressed time frame compared to the one on lower energies and the higher cross-section depending on the reaction. Examples of such measurements are the neutron induced fission experiments at the new experimental area EAR-2 at the n_TOF facility at CERN. Although analytical expressions to account for this inefficiency exist in literature, the introduced corrections are not always sufficient to retrieve the true reaction rate, therefore a different approach is mandatory. This work explores the possibility to quantify the counting losses using detector emulation devices and exponential fits in waiting time distributions. The methodology is benchmarked in the test case of the standard 238U(n,f) cross-section with reference to 235U(n,f) for bandwidths up to 1.9 MHz and counting losses that exceed 60%.

All-Fiber Passive Alignment-Free Depolarizers Capable of Depolarizing Narrow Linewidth Signals

We report on two fully-fiberized, input polarization independent depolarizer configurations that do not need any alignment once fabricated. This makes them suitable for real-world applications. The first configuration uses polarization-maintaining (PM) fibers and relatively few components. The second configuration uses standard (non-PM) single mode fibers to introduce the large time delays needed to enable narrow-linewidth signal depolarization, albeit at the cost of a slightly increased component count and insertion loss. We theoretically analyze the depolarization performance of the proposed configurations as a function of various depolarizer parameters. Subsequently, we design the depolarizers considering the imperfections of standard commercially available components. Finally, we fabricate prototypes of both configurations, characterize their depolarization performance using sources of variable linewidth, and compare the experimental results with theoretical analysis. The fabricated depolarizers are shown to be capable of the depolarization of 20 MHz and 1 MHz linewidth signals with residual degree of polarization below 4%.

Geographic HWMP (Geo‐HWMP) routing method for AMI network with lossless packet forwarding

Advanced metering infrastructure (AMI) transfers time-based information and critical data between the consumer site and central control centre. AMI network needs maximum connectivity among the smart meters that are data generators as well as forwarders. Wireless mesh network (WMN) is used to deploy AMI network. IEEE 802.11s standard is used for WMN uses airtime metric to choose next hop for the path. In this study, the position of the next hop is also considered to reduce the length of the path. The coverage area is divided into number of sectors and ranges with different radii. The next hop is selected from the sector in the direction towards the destination based on the weighted airtime metric, where the weight refers to the link quality. The sector division reduces the length of the path, and the link quality-based selection reduces packet loss and ensures reliable communication. The performance of the proposed method is demonstrated, and it is compared with hybrid wireless mesh routing protocol (HWMP) and state-of-the-art schemes, namely, greedy and compass in terms of hop count, end-to-end delay and packet loss ratio. The simulation results show that the proposed method generates routing path with minimum end-to-end delay and packet loss ratio.