Добірка наукової літератури з теми "Rate-Optimal RS"

We investigate the statistical and computational requirements for distributed kernel ridge regression with randomized sketching (DKRR-RS) and successfully achieve the optimal learning rates with only a fraction of computations. More precisely, the proposed DKRR-RS combines sparse randomized sketching, divide-and-conquer and KRR to scale up kernel methods and successfully derives the same learning rate as the exact KRR with greatly reducing computational costs in expectation, at the basic setting, which outperforms previous state of the art solutions. Then, for the sake of the gap between theory and experiments, we derive the optimal learning rate in probability for DKRR-RS to reflect its generalization performance. Finally, to further improve the learning performance, we construct an efficient communication strategy for DKRR-RS and demonstrate the power of communications via theoretical assessment. An extensive experiment validates the effectiveness of DKRR-RS and the communication strategy on real datasets.

With the explosive increase in demand for wireless communication, the issue of wireless communication security has also become a growing concern. In this paper, we investigate a novel covert communication for unmanned aerial vehicle (UAV)-assisted uplink rate-splitting multiple access (RSMA) systems, where a UAV adopts the rate-splitting (RS) strategy to increase the total transmission rate while avoiding deteriorating the covert transmission of a ground user. In the proposed system, a ground user and a UAV adopt the RSMA scheme to simultaneously communicate with a base station surveilled by an evil monitor. The UAV acts as both the transmitter and the friendly jammer to cover the ground user’s transmission with random power. To maximize the expected sum rate (ESR), we first study the RS strategy and obtain the optimal power allocation factor. Then, the closed-form of minimum detection error probability (DEP), ESR, and optimal target rate of the UAV are derived. Constrained by the minimum DEP and expected covert rate (ECR), we maximize the ESR by optimizing the position and target rate of the UAV. Numerical results show that the proposed scheme outperforms the traditional NOMA systems in terms of ESR with the same DEP and ECR.

Background: To evaluate the diagnostic accuracy and clinical utility of the acute aortic dissection detection risk score (ADD-RS) alone or with D-dimer as a screening test to exclude acute aortic syndrome. Methods: We conducted a systematic review and meta-analysis of studies examining the diagnostic accuracy of ADD-RS. We searched MEDLINE, Embase and Cochrane Controlled Register of Trials up to 12 December 2018. Results: We identified nine studies involving 26,598 patients for ADD-RS alone and 3421 patients with D-dimer. Overall, the methodological quality based on the Quality Assessment of Diagnostic Accuracy Studies 2 was moderate to high. Bivariate meta-analyses showed that the pooled sensitivities were 0.94 (95% confidence interval (CI) 0.90, 0.96) at the threshold of ADD-RS ≥1, 0.46 (95% CI, 0.34, 0.59) at ADD-RS ≥2, 1.00 (95% CI 0.99, 1.00) at ADD-RS ≥1 with D-dimer and 0.99 (95% CI 0.97, 1.00) at ADD-RS ≥2 with D-dimer. For the low prevalence population, failure rate and efficiency were 0.8% and 38.3% at ADD-RS ≥1, 0.03% and 14.5% at ADD-RS ≥1 with D-dimer, and 0.1% and 33.6% at ADD-RS ≥2 with D-dimer, respectively. For the high prevalence population, failure rate and efficiency were 3.8% and 33.3% at ADD-RS ≥1, 0.2% and 12.3% at ADD-RS ≥1 with D-dimer and 0.6% and 28.4% at ADD-RS ≥2 with D-dimer, respectively. Conclusions: ADD-RS alone or with D-dimer was a useful screening test with high sensitivity to exclude acute aortic syndrome. However, the optimal threshold of ADD-RS alone or with D-dimer may depend on the clinical setting.

An innovative performance study of an offset pulse-position modulation (OPPM) scheme is presented in this work with Reed–Solomon (RS) and low-density parity-checking (LDPC). The main aim is to resolve the errors of OPPM three using an RS or LDPC as a sporadic set of forward error correction (FEC). In this regard, the separate FEC has been utilized with coding that is based on multi-level, and waveform shaping based on the trellis. To systematically conduct this research, the greatest transmission efficiency that associated with the optimum RS code rates at different fiber normalization bandwidths is evaluated. Furthermore, the transmission efficiencies, channel extension, as well as the required number of photons per pulse of OPPM before and after the integration with RS or LDPC are compared. The results indicate an enhancement of mitigating the system's bit error rate and delivering more error-free data to the receiver in the occasion of applying the optimal settings of the RS or LDPC.

Dicode Pulse Position Modulation (DiPPM) has been presented as a new coding technique with several improvements over earlier PPM formats. Few analyses and experimental results have been published because it is a new coding scheme. To overcome the problem of bandwidth utilization in current PPM formats, DiPPM can be employed. The line rate is twice as fast as the original data rate. In order to increase DiPPM's error performance, two types of Forward Error Correction (FEC) codes, Reed-Solomon (RS) code and low-density parity-check (LDPC) code, are investigated in this article. When RS and LDPC function at their optimal parameters, the results show an improvement in DiPPM system error performance. The error performance of an uncoded DiPPM system was compared to that of a DiPPM-encoded LDPC system and a system utilizing the Reed-Solomon algorithm. Transmission efficiency is measured by the number of photons per pulse and bandwidth widening. When the bandwidth is 1x103 times or more than the initial data rate, DiPPM with LDPC code exceeds uncoded DiPPM and DiPPM with RS, using 1.821 x 103 photons per pulse, with a codeword length of 27 and code rate of 0.75.

Fertilization plays a critical role in tomato production across the state of Florida. However, appropriate fertilization management depends on four major components (4Rs): right source, right rate, right placement, and right timing. Farming practices that follow the 4Rs can provide nutrients for optimal tomato productivity while minimizing the risk of nutrient losses and adverse environmental effects, both of which are important to the development of agricultural sustainability. This 6-page fact sheet discusses the 4Rs as well as conventional dry source fertilizers, controlled-release or slow-release source fertilizers, and liquid source fertilizers. Written by Qingren Wang, Guodong Liu, Kelly Morgan, and Yuncong Li, and published by the UF Department of Horticultural Sciences, October 2015. HS1269/HS1269: Implementing the Four Rs (4Rs) in Nutrient Stewardship for Tomato Production (ufl.edu)

HighlightsThis study focused on the base cutting energy consumption for sugarcane stools instead of single stalks, thus being more consistent with actual field harvesting.The energy consumption increased with increasing rotational speed (RS) and stool diameter (SD), while it decreased with increasing tilt angle (TA) and feed rate (FR).Each pair of levels of each factor was compared using Duncan’s multiple range test. Three factors (RS, SD, and FR) had significant effects on energy consumption at 95% confidence level, while one factor (TA) had no significant effect.The order of influence and the optimal combination of the four factors to minimize the energy consumed during base cutting were determined.Abstract. Previous studies on contra-rotating basecutter designs based on supported cutting have mainly focused on the base cutting energy consumption for single sugarcane stalks instead of sugarcane stools. However, in the actual base cutting process, a basecutter typically cuts multiple sugarcane stalks (in one sugarcane stool) simultaneously. Therefore, this study investigated how the rotational speed (RS) and tilt angle (TA) of the cutting discs, the sugarcane stool diameter (SD), and the feed rate (FR) affected the energy consumed when cutting cane stools using a contra-rotating cutting platform. Four single-factor experiments and an orthogonal experiment were performed using a Taguchi orthogonal experimental design, and each group was replicated five times. The results of the single-factor experiments showed that the energy consumption was proportional to RS and SD, while it was negatively correlated with TA and FR. The significance of the difference between each pair of levels of each factor was investigated using Duncan’s multiple range test. According to the results of the orthogonal experiment, RS, SD, and FR had significant influences on the base cutting energy consumption at the 95% confidence level; however, TA had no significant influence. The order of influence of the four factors was SD > FR > RS > TA (18.45 > 18.39 > 12.91 > 9.06), and the optimal factor-level combination for minimizing the cutting energy was RS2, TA4, SD1, and FR3 (200 rpm disc RS, 20° disc TA, 60 mm SD, and 1.0 m s-1 FR). An understanding of the relationships between energy consumption and its influencing factors can serve as a valuable reference for researchers seeking to optimize the design of contra-rotating basecutters, which could lead to increased energy efficiency and a reduction in energy consumption during sugarcane harvesting. Keywords: Contra-rotating basecutter, Energy consumption, Orthogonal experiment, Single-factor experiment, Sugarcane stools, Supported cutting.

Richter syndrome (RS) is defined as the transformation of chronic lymphocytic leukemia (CLL) into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). RS occurs in approximately 2% to 10% of CLL patients during the course of their disease, with a transformation rate of 0.5% to 1% per year. A combination of germline genetic characteristics, clinical features (eg, advanced Rai stage), biologic (ζ-associated protein-70+, CD38+, CD49d+) and somatic genetic (del17p13.1 or del11q23.1) characteristics of CLL B cells, and certain CLL therapies are associated with higher risk of RS. Recent studies have also identified the crucial role of CDKN2A loss, TP53 disruption, C-MYC activation, and NOTCH1 mutations in the transformation from CLL to RS. An excisional lymph node biopsy is considered the gold standard for diagnosis of RS; a 18F-fluorodeoxyglucose positron emission tomography scan can help inform the optimal site for biopsy. Approximately 80% of DLBCL cases in patients with CLL are clonally related to the underlying CLL, and the median survival for these patients is approximately 1 year. In contrast, the remaining 20% of patients have a clonally unrelated DLBCL and have a prognosis similar to that of de novo DLBCL. For patients with clonally related DLBCL, induction therapy with either an anthracycline- or platinum-based regimen is the standard approach. Postremission stem cell transplantation should be considered for appropriate patients. This article summarizes our approach to the clinical management of CLL patients who develop RS.

HighlightsThe objective of this study was to investigate the parameters of a new type of contra-rotating basecutter on the energy consumption during support cutting.Rotational speed of basecutting discs and feeding rate of sugarcane stalks had significant influence on the cutting energy consumption, while tilt angle of discs and blade number on each disc had no significant influence on it.The influencing order of the factors used in this research was disc rotational speed > feeding rate > disc tilt angle > blade number, and the basecutting energy was minimum when the above four factors were 150 rpm, 1.0 m·s-1, 20°, and 4.Abstract. Previous studies on a new type of contra-rotating basecutter that was designed based on the support-cutting theory mainly focused on the relationship between the cutting quality of sugarcane stalks and the basecutter parameters. However, the relationship between these factors and the energy consumption during basecutting was not studied. Therefore, a contra-rotating basecutting platform was developed to investigate how the rotational speed (RS) and tilt angle (TA) of the cutting disc, cutting blade number (BN), and sugarcane stalk feeding rate (FR) affected basecutting energy consumption through a series of bench tests, which included four single-factor experiments and a four-factor four-level orthogonal experiment. Results of the single-factor experiments showed that the basecutting energy consumption increased with increasing RS and BN, while the energy consumption decreased with increasing TA and FR. In addition, t-test results among the four levels of each factor indicated that the differences were not significant (p > 0.05) for level 3 vs. 4 of TA, for level 2 vs. 3 and level 2 vs. 4 of BN, and for level 2 vs. 3 of FR. However, there were significant differences between the other two levels of each factor. ANOVA of the orthogonal experiment results showed that RS and FR had significant influence on basecutting energy consumption, while TA and BN had no significant influence. The influencing order of the four factors on energy consumption was RS > FR > TA > BN (F-values of 19.64 > 10.04 > 4.95 > 2.45). Finally, the optimal combination was determined as 150 rpm for RS, 20° for TA, 4 for BN, and 1.0 m.s-1 for FR. This study provides references for the optimal design of contra-rotating basecutters, which could greatly reduce energy consumption during sugarcane harvest. Keywords: Contra-rotating basecutter, Energy consumption, Orthogonal experiment, Single-factor experiment, Support-cutting theory.

In this paper, we investigate the physical layer security of cooperative two-way relay transmission systems using the amplify-and-forward (AF) protocol in the presence of an eavesdropper. A joint relay selection (RS) and power allocation (PA) scheme is proposed to protect the source-destination transmission against the eavesdropper. However, due to the high computational complexity, it is difficult to obtain the optimal solution for the system secrecy rate. Fortunately, an approximate optimal solution by using the particle swarm optimization (PSO) algorithm is derived. In the simulations, we use random relay selection with optimal power allocation (RRS-OPA) and equal power allocation with optimal relay selection (EPA-ORS) as benchmark schemes to verify the effectiveness of the proposed method. The simulation results show that the proposed method outperforms both RRS-OPA and EPA-ORS and significantly improves the system performance with low complexity.

碩士
淡江大學
電機工程學系碩士班
102
As the Internet grows, Wireless Fidelity (Wi-Fi) has become more and more popular after the upgrades of transmission rate and transmission volume, which is attracting more network researchers in the study of high-quality video transmission. Meanwhile, more Internet users choose to connect to Internet services with mobile devices, like Tablets PCs and Smartphones. Of the many Internet services, video streaming is a frequently used Internet service. The appearance of MPEG-4 has made video streaming transmission become easier, which is the first video streaming protocol that includes network abstraction layer in it. The transmission of live streaming video has become better thanks to MPEG-4’s good network adaptability and its great fault tolerance on packet loses. However, there are still many unsolved problems such as packet loss and burst packet error.Forward Error Correction (FEC) is a common technology to protect data loss by redundant packets. Today there are various kinds of FEC to explore how to adaptively adjust the redundant packet amount and make adequate redundant packet overcome source error and loss. Both block size and packet size would affect the screening rate of source error and loss. When block size is small then the screening rate, it would be better than the case that block size is large; The impact on the quality of video streaming is greater when smaller packets are used. In this paper, we study the packet loss impact on the transmission quality of MPEG transmission with FEC in wireless networks. We are not only to consider the impacts in distributed packet loss, but also to study the impact in burst packet loss, which would affect the video transmission quality. Finally, we propose a new scheme called “Dynamically Adjust Block Size and Block Size (DABSPS)”. DABSPS adjusted the transmission packet size according to the wireless network environment, which reduced the impact on video quality and FEC packet screening error rate.

Cognitive radio (CR) promises to significantly improve the utilization of scarce wireless spectrum. In the underlay mode of CR, which is the focus of the thesis, a secondary user (SU) can simultaneously transmit on the same band as a higher priority primary user (PU) so long as the interference it causes to the PU must be constrained. These interference constraints severely limit the performance of the SUs. Cooperative relaying combined with selection exploits spatial diversity to improve the performance of interference-constrained SUs. In it, one among the available relays is selected for every instantaneous channel power gains of the various links that include the secondary communication links as well as the interference links between the secondary transmitters and the primary receiver. The mapping between the channel power gains and the selected relay is determined by the relay selection (RS) rule employed by the secondary network. Furthermore, it also depends on the interference constraint, which sets underlay CRapart from conventional wireless communications. Although the peak interference constraint is well-studied in the literature on underlay CR, cooperative relaying for the less conservative average interference constraint has not been as thoroughly studied. In this thesis, we focus on developing optimal RS rules that either minimize the average symbol error probability (SEP) or maximize the average rate of the secondary network that is subject to an average interference constraint. We first develop an SEP-optimal RS rule and its two practically implementable variants when the relays are not aware of the instantaneous state of the direct source-to-destination (SD) link. The proposed rules determine which relay to select and whether to select none of the relays at all as a function of the various channel power gains. They outperform several ad hoc RS rules proposed in the literature for underlay CR and generalize the conventional interference-unconstrained RS rule. Next, we present a novel, SD-aware SEP-optimal RS rule for an average interference-constrained underlay CR network. Akey point that the rule highlights -- for the first time -- is that, for the average interference constraint, the signal-to-interference-plus-noise-ratio (SINR) ofthe direct SD link affects the choice of the optimal relay. Furthermore, as the SINR increases, the odds that no relay transmits increase. We also propose a low feedback and near-optimal variant of the SD-aware SEP-optimal RS rule that requires just one bit of feedback about the state of the direct SD link to the relays. Compared to the SD-unaware RS rules, these rules markedly reduce the SEP by up to two orders of magnitude.We then analyze the average SEPs and diversity order of the proposed RS rules to quantify their performance. Thereafter, we propose a rate-optimal RS rule that maximizes the fading-averaged transmission rate of an average interference-constrained underlay CR network. It differs functionally from the several ad hoc incremental relaying schemes proposed in the literature, but requires a feedback overhead that is comparable to them. We then analyze the average rate of the secondary network for this RS rule. We gain several insights by studying the asymptotic regimes of low and high average SINRs. Lastly, we study a practically-motivated channel state information (CSI) model for an underlay CR network with multiple primary receivers, in which the channel gains of only a subset of the interference links are available at the source and relays. Moreover, this available CSI is imperfect due to channel estimation error. Based on such incomplete and imperfect CSI, the source and relays back-off their transmit powers in order to satisfy an interference outage constraint. We derive the outage probability and average rate of the secondary network for the rate-optimal RS rule. An interesting observation that comes out of our study is that full diversity order is still achievable even with such incomplete and imperfect CSI.

There is direct proportionality between ultimate tensile stress (UTS) and residual stresses (RS). Residual stresses gradually decrease with decreasing cooling/quenching rates. Quenching in cold water develops highest, whereas air cooling produces lowest, residual stresses. Significant increase in RS is observed in specimens with low dendrite arm spacing (high solidification rate), while lower residual stresses are measured in specimens with high dendrite arm spacing (low solidification rate). For I-4 and V-6 engine blocks, there is refinement in microstructure due to the increase in solidification rate along the cylinder length. The developed residual stresses are normally tensile in both engine types. Air cooling following solution heat treatment produces higher RS compared to warm water and cold water quenching. Solution heat treatment and freezing lead to maximum RS relaxation where 50% of the stresses are reduced after the solution heat treatment step. Aging time and temperature are directly proportional to the residual stresses relaxation. Relaxation of RS also depends on the geometry and size of the workpiece. It should be mentioned here that the I-4 and V-6 cylinder blocks were provided by Nemak-Canada (Windsor-Ontario-Canada). Residual stress measurements technique and procedure are typical of those used by the automotive industry in order to provide reliable data for industrial applications supported by intensive experiments.

Basel cell carcinoma (BCC) is the most common human skin malignancy. Its incidence has increased significantly in Australia, Europe and North America over the past decade. A number of modalities are currently used for treatment of BCC, including cryosurgery which offers a potential for high cure rate, low cost, minimal bleeding and good cosmetic effect. However, cryosurgery is not used frequently for BCC because no current method exists to design adequate treatment parameters. We present a numerical analysis on the thermal history of the target tissue during cryosurgery of a nodular BCC using liquid nitrogen (LN2) spray. The model uses Pennes equation to describe the heat transfer within the target tissue. A convective thermal boundary is used to describe the heat interaction between the tissue and LN2, and the apparent heat capacity method is applied to address the tissue phase change process. A parametric study is conducted on the convective heat transfer coefficient (hs: 104~106 W/m2·K), cooling site area (rs/R0: 0.5~1.0) and spray time (t: 0~30 sec.), with the objective to understand the thermal history during tissue freezing, including lethal temperature (-50 °C) and cooling rate (CR). Results demonstrate that propagation of the lethal isotherm is sensitive to the convective heat transfer coefficient, hs, with a range of 104~5×104 W/m2·K. Increasing the cooling site area can significantly enhance cooling efficiency, producing dramatic increase in the amount of tissue encompassed by the lethal isotherm. The cooling rate (CR) shows a highly dynamic distribution during the cooling process: the highest CR drops quickly from 140 °C/sec. (t=0.5 sec.) to 20 °C/sec. (t=5 sec.). The highest CR is initially located close to the cooling site but moves toward the inside of the tissue as treatment proceeds. The model presented herein provides a simulation tool for treatment planning of cryosurgery using LN2 spray, in which the protocol parameters, e.g. cooling site area and spray time, can be determined for an optimal outcome. The quantitative predictions on the propagation of lethal isotherm and the distribution of CR should help to optimize cryosurgery efficacy.