Optimization Algorithm for Delay Estimation Based on Singular Value Decomposition and Improved GCC-PHAT Weighting.

The accuracy of time delay estimation seriously affects the accuracy of sound source localization. In order to improve the accuracy of time delay estimation under the condition of low SNR, a delay estimation optimization algorithm based on singular value decomposition and improved GCC-PHAT weighting (GCC-PHAT-ργ weighting) is proposed. Firstly, the acoustic signal collected by the acoustic sensor array is subjected to singular value decomposition and noise reduction processing to improve the signal-to-noise ratio of the signal; then, the cross-correlation operation is performed, and the cross-correlation function is processed by the GCC-PHAT-ργ weighting method to obtain the cross-power spectrum; finally, the inverse transformation is performed to obtain the generalized correlation time domain function, and the peak detection is performed to obtain the delay difference. The experiment was carried out in a large outdoor pool, and the experimental data were processed to compare the time delay estimation performance of three methods: GCC-PHAT weighting, SVD-GCC-PHAT weighting (meaning: GCC-PHAT weighting based on singular value decomposition) and SVD-GCC-PHAT-ργ weighting (meaning: GCC-PHAT-ργ weighting based on singular value decomposition). The results show that the delay estimation optimization algorithm based on SVD-GCC-PHAT-ργ improves the delay estimation accuracy by at least 37.95% compared with the other two methods. The new optimization algorithm has good delay estimation performance.

Design of High-Performance Lead-Free Quaternary Antiperovskites for Photovoltaics via Ion Type Inversion and Anion Ordering.

The emergence of halide double perovskites significantly increases the compositional space for lead-free and air-stable photovoltaic absorbers compared to halide perovskites. Nevertheless, most halide double perovskites exhibit oversized band gaps (>1.9 eV) or dipole-forbidden optical transition, which are unfavorable for efficient single-junction solar cell applications. The current device performance of halide double perovskite is still inferior to that of lead-based halide perovskites, such as CH3NH3PbI3 (MAPbI3). Here, by ion type inversion and anion ordering on perovskite lattice sites, two new classes of pnictogen-based quaternary antiperovskites with the formula of X6B2AA' and X6BB'A2 are designed. Phase stability and tunable band gaps in these quaternary antiperovskites are demonstrated based on first-principles calculations. Further photovoltaic-functionality-directed screening of these materials leads to the discovery of 5 stable compounds (Ca6N2AsSb, Ca6N2PSb, Sr6N2AsSb, Sr6N2PSb, and Ca6NPSb2) with suitable direct band gaps, small carrier effective masses and low exciton binding energies, and dipole-allowed strong optical absorption, which are favorable properties for a photovoltaic absorber material. The calculated theoretical maximum solar cell efficiencies based on these five compounds are all larger than 29%, comparable to or even higher than that of the MAPbI3 based solar cell. Our work reveals the huge potential of quaternary antiperovskites in the optoelectronic field and provides a new strategy to design lead-free and air-stable perovskite-based photovoltaic absorber materials.

Salvage Surgery for Recurrent Tongue Cancer With Contralateral Neck Metastasis.

PURPOSE: Treatment recommendations have been widely reported for primary tongue squamous cell carcinoma (TSCC) with contralateral neck metastases (CNMs), but little is known concerning recurrent TSCCs with CNMs, especially in patients who have undergone ipsilateral neck dissection. The aim of this study was to estimate overall survival (OS) and to identify prognostic factors associated with OS in patients treated for recurrent TSCCs. PATIENTS AND METHODS: We performed a retrospective cohort study of patients who underwent salvage surgery (SS) for recurrent TSCC in our institution between January 2010 and December 2014. Before SS, all patients had been surgically treated for primary TSCC with ipsilateral neck dissection. The primary outcome variable was OS, and the patients were grouped by the primary predictor variable of CNM status for comparison. Other heterogeneous variables of interest included demographics, medical histories, clinicopathologic characteristics, surgical data, and adjuvant treatment modalities. In addition, the midline involvement and anatomic subsites of local recurrences were evaluated. Univariate log-rank and Cox regression tests were used for statistical analyses. RESULTS: The study sample included 177 subjects with a mean age of 55.4 years, and 44.6% were males. The median OS was 18 months. Within the entire cohort, the incidence of CNM was 23.7% (n = 42), with an inclination (n = 30) for contralateral level I or II. Factors associated with improved survival included CNM (hazard ratio [HR], 2.108; 95% confidence interval [95% CI], 1.341 to 3.315; P = .001), disease-free interval (HR, 0.601; 95% CI, 0.387 to 0.934; P = .023), and local recurrence subsite score (HR, 3.276; 95% CI, 0.924 to 11.623; P = .001). CONCLUSIONS: Patients with both recurrent TSCCs and CNMs had a dismal prognosis (OS rate, 16.2%) compared with those without CNMs (OS rate, 52.7%). SS for TSCC patients with collateral failures should be used cautiously because of the very unfavorable outcomes.

The locatability of Pearson algorithm for multi-source location in complex networks.

We study locating propagation sources in complex networks. We proposed an multi-source location algorithm for different propagation dynamics by using sparse observations. Without knowing the propagation dynamics and any dynamic parameters, we can calculate node centrality based on the character that positive correlation between inform time of nodes and geodesic distance between nodes and sources. The algorithm is robust and have high location accuracy for any number of sources. We study locatability of the proposed source location algorithm and present a corresponding strategy to select observer nodes based on greedy algorithm. All simulations on both model and real-world networks proved the feasibility and validity of this algorithm.

A bibliometric analysis on studies of nanomedicine applications in head and neck squamous cell carcinoma.

BACKGROUND: Bibliometric analysis highlights the pivotal studies and topics that have shaped the understanding and management of a disease in its designated field. Herein, original articles on the applications of nanotechnology in head and neck squamous cell carcinoma (HNSCC) were characterized and analyzed. METHODS: A comprehensive search was carried out using a bibliometric methodology, and eligible articles on nanomedicine research in HNSCC were retrieved from the Scopus database. RESULTS: A total of 309 eligible articles were retrieved, and the total citation count was 7,468. An ascending trend in citation count was observed since 2004, which increased substantially between 2014 and 2019. There were 144 (52.7%) original articles on oral cavity carcinomas. Chemotherapy (n=53, 19.4%), chemoprevention (n=35, 11.3%), and photodynamic therapy (n=23, 8.4%) were the three most published topics on the applications of nanotechnology in the therapy of HNSCC. Sentinel node detection (n=25, 9.2%) and noninvasive cancer diagnosis (n=22, 8.1%) were the two most published topics in the diagnostic area of HNSCC. A vast majority of these articles were preclinical studies, and only four articles (1.5%) were phase I/II clinical studies on chemotherapy and radiotherapy. CONCLUSIONS: To the best of our knowledge, this is the first study to analyze the bibliometric characteristics of original articles on nanomedicine in HNSCC. The results of this study not only provide a historical perspective on the scientific evolution in this field, but also revealed the trends and key topics within it that may help facilitate further research.

[Finite element analysis of clear aligners in extractive cases].

PURPOSE: This study analysed the mechanical features of the extraction space closure in clear aligners through mechanical research. METHODS: A patient with four first premolars extraction was chosen as sample, and four plans with clear aligners for space closure were designed, including anterior retraction entirely, anterior retraction dispersedly, posterior movement mesially and posterior movement dispersedly. Finite element analysis was performed separately. RESULTS: In anterior retraction, when there was no anterior space, the force acted on them more evenly, and the posteriors needed to provide more anchorage; when anterior space existed, the force acted on the central incisors first and largely, and the posteriors needed to provide less anchorage. In posterior anchorage, when the posteriors moved entirely with mesial movement, it might help to protect second premolar's anchorage while molars would receive more mesial force; when the posteriors moved separately without designed movement, the second premolar would undertake more anchorage and more tendency to incline mesially; when the posteriors moved entirely without designed movement, the anchorage would distribute more evenly. CONCLUSIONS: Selection of the way of retracting anteriors should be based on the difference of stress distribution in different ways in addition to individual discrepancy and clinical facts. Selection of the way of moving posteriors should be based on the distribution of anchorage as well as avoiding posterior open bite. Less amount of correction in each step has better axial control.

A carbon-oxygen-bridged ladder-type building block for efficient donor and acceptor materials used in organic solar cells.

A carbon-oxygen-bridged ladder-type donor unit (CO5) was invented and prepared via an "intramolecular demethanolization cyclization" approach. Its single crystal structure indicates enhanced planarity compared with the carbon-bridged analogue indacenodithiophene (IDT). Owing to the stronger electron-donating capability of CO5 than IDT, CO5-based donor and acceptor materials show narrower bandgaps. A donor-acceptor (D-A) copolymer donor (PCO5TPD) and an A-D-A nonfullerene acceptor (CO5IC) demonstrated higher performance than IDT-based counterparts, PIDTTPD and IDTIC, respectively. The better performance of CO5-based materials results from their stronger light-harvesting capability and higher charge-carrier mobilities.