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The inferior thermoelectric performance of n-type PbTe limits the overall conversion efficiency in PbTe-based thermoelectric devices. Here, we introduce Sb and Cu2Te into n-type Nb-doped PbTe for achieving ultra-high thermoelectric performance. The co-doping of Sb and Cu effectively optimizes carrier concentration to compensate for the resonant level in Nb-doped PbTe alloys, and consequently achieves superior electrical performance over a wide temperature range. Meanwhile, by combining extended X-ray absorption fine structure and exhaustive electron microscopy investigations, we found Nb and Sb substitutions at Pb sites induce atomic disorders, such local mass fluctuation and local strain variation, in the lattice, and Cu2Te further results in microsized segregations and nanoprecipitates, which significantly suppress lattice thermal conductivity. Eventually, a peak ZT of ∼ 1.32 at 823 K and a high average ZTave ∼ 1.01 in the range from 323 to 823 K are achieved in the Pb0.975Nb0.02Sb0.005Te-0.004Cu2Te. Based on our findings, we innovatively employ comprehensive characterization to reveal the origin of ultrahigh thermoelectric performance in n-type Nb-doped PbTe within a wide temperature range, which should be generalized to other thermoelectric materials.

Introducing resonant levels is a potent strategy to improve the thermoelectric properties of the thermoelectric systems. However, the beneficial effect of resonant levels tends to be weakened with rising temperature for the PbTe system. This motivates us to introduce dynamic doping of Cu into Cr-doped n-type PbTe to achieve the fully optimized carrier transport over a wide temperature range. As a consequence, an extraordinary figure of merit, ZT of ∼ 0.55 at room temperature, a peak ZT of ∼ 1.31 at 773 K and an average ZT of ∼ 1.02 in the range of 323 to 823 K are obtained in the Pb0.975Cr0.025Te-0.2%Cu. Additionally, how co-doped of Cr and Cu contributes to suppressing thermal transports is still ambiguous. Herein, we employ comprehensive electron microscopy investigations to reveal that the synergistic incorporation of Cr and Cu into the PbTe matrix results in a series of phonon scattering sources, including massive point defects, high-density of nanoscale precipitates, microscale secondary phases, and dense grain boundaries, which can significantly reduce the lattice thermal conductivity by enhancing phonon scattering. This work clarifies the fundamental Cr-doping mechanism in PbTe and demonstrates that dynamic Cu-doping engineering is an effective approach to boosting thermoelectric performance, which should be applied in other thermoelectric materials.

The development of n-type high-performance PbTe thermoelectric materials for matching its p-type counterparts is an urgent matter to expand its practical applications. Here, we introduce Ag2Te into n-type Pb0.975Cr0.025Te for achieving a high peak figure of merit of 1.5 at 773 K. Such a high value is attributed to the synergistic optimization of carrier and phonon transports by Ag2Te introducing and the dynamic doping of Ag. From the detailed structure and property analysis, we found that Ag2Te nanoprecipitates establish coherent interfaces and hence potential barriers with the matrix to induce energy-dependent carrier scattering and maintain relatively high carrier mobility, leading to an optimal electrical-transport properties over a wide temperature range. Moreover, we employ comprehensive electron microscopy investigations and approximate Debye-Callaway model to reveal the origin of the significantly reduced lattice thermal conductivity in Ag2Te-alloyed Pb0.975Cr0.025Te. The strategies used here provide an effective method for designing high-performance thermoelectric material systems.

Gasless transumbilical extracorporeal laparoscopic-assisted appendectomy is an approach used increasingly to treat uncomplicated acute appendicitis (UAA). However, there is limited information on its clinical effects and value in the Chinese pediatric population. This study retrospectively reviewed patients with UAA treated in two pediatric institutions from January 2018 through October 2021. Enrolled patients were divided into two groups by operative technique: gasless transumbilical laparoscopic-assisted appendectomy (gasless-TULAA, n=142) and conventional laparoscopic appendectomy (CLA, three-port, n=126). The perioperative clinical data, including age, sex, body mass index (BMI), operation time, time to postoperative ambulation, time to first postoperative exhaust, hospitalization expenses, and postoperative complications (incision infection, intestinal obstruction, and residual abdominal abscess), were compared between the two groups. Operations in both groups were successfully conducted without converting to open surgery. There were no significant differences (p > 0.05) in age and BMI in the two groups. Compared with CLA, gasless-TULAA showed significantly shorter operation time, earlier postoperative ambulation, shorter postoperative exhaust time, and lower hospital cost (p < 0.001). All patients were followed for 3 months, and postoperative complications were observed in three patients: two patients in the gasless-TULAA group (one with surgical wound effusion, one with intra-abdominal abscess), and one patient in the CLA group (surgical wound infection); there was no significant difference between the groups. Notably, 38 patients initially treated by gasless-TULAA were converted because of intraoperative factors. The gasless-TULAA technique had potential benefits: shortened operation time, better outcome, and greater cost-efficiency. These superiorities are worthy of future large-scale prospective study.

Gasless transumbilical extracorporeal laparoscopic-assisted appendectomy is an approach used increasingly to treat uncomplicated acute appendicitis (UAA). However, there is limited information on its clinical effects and value in the Chinese pediatric population. This study retrospectively reviewed patients with UAA treated in two pediatric institutions from January 2018 through October 2021. Enrolled patients were divided into two groups by operative technique: gasless transumbilical laparoscopic-assisted appendectomy (gasless-TULAA, n=142) and conventional laparoscopic appendectomy (CLA, three-port, n=126). The perioperative clinical data, including age, sex, body mass index (BMI), operation time, time to postoperative ambulation, time to first postoperative exhaust, hospitalization expenses, and postoperative complications (incision infection, intestinal obstruction, and residual abdominal abscess), were compared between the two groups. Operations in both groups were successfully conducted without converting to open surgery. There were no significant differences (p > 0.05) in age and BMI in the two groups. Compared with CLA, gasless-TULAA showed significantly shorter operation time, earlier postoperative ambulation, shorter postoperative exhaust time, and lower hospital cost (p < 0.001). All patients were followed for 3 months, and postoperative complications were observed in three patients: two patients in the gasless-TULAA group (one with surgical wound effusion, one with intra-abdominal abscess), and one patient in the CLA group (surgical wound infection); there was no significant difference between the groups. Notably, 38 patients initially treated by gasless-TULAA were converted because of intraoperative factors. The gasless-TULAA technique had potential benefits: shortened operation time, better outcome, and greater cost-efficiency. These superiorities are worthy of future large-scale prospective study.

Sistema de NLP capaç d'entendre preguntes i respondre utilitzant l'ontologia de DBpedia.

With the population of urban vehicle, parking resources are becoming scarcer and scarcer. Additionally, the lack of parking information, unreasonable parking charging and uncertain parking demand aggravates parking problems. With the advent of the Internet era as well as the improvement of urban smart level, parking reservation has become one of the most effective ways to solve parking problems. By this way a mathematical liner program is proposed to choose the optimum parking price in order to maximize the revenue of a parking system operated by a private owner. A price variance minimization is also added to the model in order to have a tool to decide about new possible tariffs. Furthermore, numerical experiments are given to show the effectiveness of the model., Outgoing

Outgoing

In this project the Ground Delay Program (GDP) and the Collaborative Decision Making (CDM) concepts have been studied. A statistical analysis on all GDPs that occurred during April of 2018 and during the year 2006 in the United States of America has been done. Some statistics have been derived on the number of GDPs and their causes. Results show that the 90% of the GDPs took place in only 13 and 16 airports, respectively. In both statistics Newark (EWR), in New York, have been the airport with more regulations. In addition, in April the 87% of the GDPs were caused by bad weather conditions versus a 74% in 2006. Furthermore, a complex study has been done at 2006 as the assigned delay and the number of affected flights per airport showing that the 90% of the total delay was assigned only in 10 airports, being Chicago the airport with more delay assigned. The same behaviour was observed with the number of affected flights: 90\% of the flights has been related to only 10 different airports and Chicago again, was the airport with more affected flights. The results of the number of affected flights and the assigned delay have indicated a relationship. However, many airports with more flights and delay are also in the highest positions of the number of GDPs per airport list. The last part of the project is a simulation of as deterministic GHP for two different scenarios using Matlab. An optimal allocation of slots to flights taking into account its cost and the number of connection passengers of each flight has been analysed. The results have shown an exponential behaviour which increases for a high airport acceptance rates and when the flights have connection passengers. Using Ratio-by-Schedule the minimum costs have been obtained.

This work presents the analytic and experimental research of de-icing method with piezoelectric transducer as actuators. For the reason of flight conditions like altitude, high and humidity. To meet the requirements for flight, deicing measures must be taken in consideration. There are lots of existing deicing methods, but the main problem is that the loss of power with them is very big increasing the consumption of fuel and decreasing the efficiency of the flight. With the development of piezoelectric ceramic technology, shear vibration deicing is more concerned for their low power consumption. Shear stress between surface and ice is generated by the forced vibration which is driven by piezoelectric. The device achieves the deicing purpose activating resonant frequencies of a structure using piezoelectric ceramic actuators to generate enough shear stress at the interface, between the surface and ice, to break the adhesion stress between them. In this study, we study the effect of shear stress generated for different distances between ceramic piezoelectric, and then analyze the relations of the shear stress and frequency. First, a numerical method was validated to assist the design of such systems. Numerical simulations were performed for the case of a flat plate testing the natural modes and harmonic response by the software ANSYS, which proves the feasibility to remove ice by piezoelectric ceramic actuator in theory. And then, validated experimentally. The model was then used to study important design parameters such as actuator positioning and the distance between them.

Implantable sensors that detect biomarkers in vivo are critical for early disease diagnostics. Although many colloidal nanomaterials have been developed into optical sensors to detect biomolecules in vitro, their application in vivo as implantable sensors is hindered by potential migration or clearance from the implantation site. One potential solution is incorporating colloidal nanosensors in hydrogel scaffold prior to implantation. However, direct contact between the nanosensors and hydrogel matrix has the potential to disrupt sensor performance. Here, we develop a hollow-microcapsule-based sensing platform that protects colloidal nanosensors from direct contact with hydrogel matrix. Using microfluidics, colloidal nanosensors were encapsulated in polyethylene glycol microcapsules with liquid cores. The microcapsules selectively trap the nanosensors within the core while allowing free diffusion of smaller molecules such as glucose and heparin. Glucose-responsive quantum dots or gold nanorods or heparin-responsive gold nanorods were each encapsulated. Microcapsules loaded with these sensors showed responsive optical signals in the presence of target biomolecules (glucose or heparin). Furthermore, these microcapsules can be immobilized into biocompatible hydrogel as implantable devices for biomolecular sensing. This technique offers new opportunities to extend the utility of colloidal nanosensors from solution-based detection to implantable device-based detection. Keywords: biomolecular sensing; Microcapsules; microfluidic fabrication; nanosensors, Juvenile Diabetes Research Foundation International (Award 17-2013-507)

Piezoelectric ceramics, especially lead zirconate titanate (PZT) ceramics, have been widely used and studied for their extraordinary and adjustable electro-mechanical properties. However, defects such as cavities and micro-cracks are unavoidable during manufacturing and operation. These defects can degrade the piezoelectric properties and undermine their performance in service. Conventional methods of determining structural reliability, such as measuring the mechanical strength of piezoelectric ceramics are destructive and inevitably cause the ceramic sample to fail after testing. Therefore, a practical non-destructive method for evaluating mechanical reliability is required. This study investigates the applicability of using partial discharge (PD) test to evaluate the reliability of piezoelectric ceramics PZT. Preliminary PD and four-point flexure tests were conducted on a soft PZT ceramic and the influence of PD test on PZT samples is discussed. Weibull analysis of the results reveal an analogy between PD inception field and mechanical strength distribution, which suggests that the PD and fracture may originate from the same group of defects in PZT. The results also show that PD occurs at low electric field in piezoelectric ceramics. In order to further understand the factors influence PD, PD behaviours are examined in different types (i.e. hard and soft) of PZT ceramics. The PD results are also compared to traditional alumina and mullite ceramic and epoxy polymer dielectric materials. In general, materials with higher permittivity or/and larger defects demonstrate a lower PD inception electric field. More PDs occur when the applied electric field is increased, especially in soft PZT. This indicates that the change in polarization during domain switching in soft PZT can facilitate PD occurrences in piezoelectric ceramics. A further study of PD under unipolar and bipolar electric field confirms this assumption. PD starts at a higher electric field under a unipolar

Treball realitzat a la Beihang University of Aeronautics and Astronautics, [ANGLÈS] This work is part of ongoing research conducted at Beihang University relating to signal generating. The primary objective of this thesis was to develop a flexible, high-performance Radio Frequency (RF) generator platform in order to facilitate research on channel response. A FPGA-based system architecture utilizing a stacked, multi-board design was created to meet this goal. A combination of a Liquid-Crystal Display (LCD), power supply, FPGA control and RF generator were employed in the new system., [CASTELLÀ] Este trabajo es parte de la investigación en curso llevado a cabo en la Universidad de Beihang en el departamento de Teoría de señal. El objetivo principal de esta tesis es el desarrollo de una plataforma flexible y de alto rendimiento para un generador de radiofrecuencia (RF) con el objetivo de facilitar el estudio en los canales de comunicación. Una arquitectura de sistema basado en FPGA utilizando un diseño multi-placa de apilamiento fue creado para cumplir con este objetivo. Una combinación de una pantalla de cristal líquido (LCD), fuente de alimentación, control FPGA y el generador de RF fueron empleados en el nuevo sistema., [CATALÀ] Aquest treball és part de la investigació en curs dut a terme a la Universitat de Beihang en el departament de Teoria del senyal. L'objectiu principal d'aquesta tesi es el desenvolupament duna plataforma flexible i de alt rendiment per una generador de radiofreqüència (RF) amb l’objectiu de facilitar l’estudi en els canals de comunicació. Una arquitectura de sistema basat en FPGA utilitzant un disseny multi-placa d'apilament va ser creat per complir amb aquest objectiu. Una combinació d'una pantalla de cristall líquid (LCD), font d'alimentació, control FPGA i el generador de RF van ser emprats en el nou sistema.

In this thesis we will focus our analysis in the inventory decisions with one specific kind of sourcing contract. More concretely, we will study and analyze the order quantities under a supply flexible contract conditions. The quantity flexibility contract in supply chain management is committed to reduce the risk of both retailers and suppliers, and optimize the profit of the whole supply chain at the same time. Under this contract, retailers are allowed to correct the base order quantity with an extra quantity order. This fact will benefit the retailer to suit the demand uncertainty. By experimental research, the thesis focuses on the limited-rational decision making of the human behavior in the operations management. The experiment is designed from the perspective of the retailer. Retailers make corresponding security quantity order decisions according to variable demand environment information. The thesis has established a mathematical model, which can derive the theoretical optimal values for the amount of extra quantity order. According to the statistical analysis of the actual quantity order, the study focuses on the differences between the actual decision and the theoretical optimum, and explains the reasons for deviation. The experiment set up four control groups to study the factors’ influence on retailers’ actual security quantity decisions by changing the reservation deposit and the product’s high or low profit margin level. The results show that the retailers are rational limited in the decision making. Their decisions are influenced by many factors, causing the ordering deviation. Through the comparison and analysis, the thesis attempts to provide a reference for retailers’ actual ordering decision, and lead to optimal largest possibly and ultimately achieve the best practices in order to try to resemble their real results with the theoretical optimum. At the same time, it’s necessary to reflect the deficiency of the research which can provide a new di, Outgoing

[ANGLÈS] The optic tract is a complex structure, not only because of its morphology, but also because of its location in the brain. This project aims to obtain the optic tract trajectories, by using diffusion MRI techniques, in an automated and reliable way, and extract diffusion characteristic parameters., [CASTELLÀ] El tracto óptico es una estructura compleja, no sólo por su morfología, sino también por su situación dentro del cerebro. Este proyecto pretende obtener la trayectoria de la vía visual con herramientas de difusión de manera automatizada y fiable, y extraer parámetros característicos asociados a MRI a lo largo de ésta., [CATALÀ] El tracte òptic és una estructura complexa, no només per la seva morfologia, sinó també per la seva situació dins del cervell. Aquest projecte pretén obtenir la trajectòria de la via visual amb eines de difusió de manera automatitzada i fiable, i extreure paràmetres característics associats a MRI al llarg d'aquesta.

Projecte final de carrera fet en col.laboració amb Beihang University, English: Nowadays, the image processing has become an important tool in many fields. For example, in Aeronautics and Astronautics this kind of applications are really useful for detecting defects on the surface of airships. On the one hand, for reducing cost due to one defect can be detected immediately and on the other hand, doing this process automatically it is possible to control things and arrive to places that a person hardly can do. In this project an automatic surface defects detector has been implemented. The software used to reach the objective is Matlab and its tool for developing users interfaces called GUIDE Tool. The results obtained are very satisfactory., Castellano: Hoy en día, el procesamiento de imágenes se ha convertido en una herramienta importante en muchos campos. Por ejemplo, en Aeronáutica y Astronáutica este tipo de aplicaciones son realmente útiles para la detección de defectos en la superficie de aeronaves. Por un lado, es posible reducir costes ya que un defecto se puede detectar de inmediato y por lo tanto arreglar antes de que se agrabe y por otro lado, haciendo este proceso de forma automática, es posible controlar factores y llegar a lugares donde una persona no puede llegar. En este proyecto, se ha diseñado un prototipo de detector de defectos en la superficie de objetos. El software utilizado para alcanzar dicho objetivo es Matlab y su herramienta para el desarrollo de interfaces de usuarios llamado GUIDE tool. Los resultados obtenidos son muy satisfactorios., Català: Avui dia, el processament d'imatges s'ha convertit en una eina important en molts camps. Per exemple, en Aeronàutica i Astronàutica aquest tipus d'aplicacions són realment útils per a la detecció de defectes en la superfície d'aeronaus. D'una banda, és possible reduir costos ja que un defecte es pot detectar immediatament i per tant arreglar abans que s'agreuji i d'altra banda, fent aquest procés de forma automàtica, és possible controlar factors i arribar a llocs on una persona no pot arribar. En aquest projecte, s'ha dissenyat un prototip de detector de defectes a la superfície d'objectes. El programari utilitzat per assolir aquest objectiu és Matlab i la seva eina per al desenvolupament d'interfícies d'usuaris anomenat GUIDE tool. Els resultats obtinguts són molt satisfactoris.

Projecte final de carrera realitzat en col.laboració amb College of Electronics and Information Engineering. Tongji University, Recently, many researchers have become interested in MANET (Mobile Ad-hoc NET- works) to construct a self-con gurable network without existing communication infras- tructure. This research presents the results of a detailed performance evaluation on several MANET routing protocols working under realistic environments. The routing protocols, mobility models and other aspects are explained and discussed in order to know how to use them properly to model real-life conditions. NS-2 and Bonnmotion were used to create the networks, services and environment characteristics in general. It is concluded which protocols can handle which applications and which not and that the performance of the protocols can be considerably di erent when more and more realistic elements are taken into account. This should be considered in further researches since the nowadays evolution of MANET will bring them soon into services of our society.