Lead-Free Piezoelectric Transducers for Microelectronic Wirebonding Applications

Author name used in this publication: K. W. KwokAuthor name used in this publication: S. H. ChoyAuthor name used in this publication: H. L. W. Chan2010-2011 > Academic research: refereed > Chapter in an edited book (author)published_fina

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

(Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-(Bi1/2Li1/2)TiO3-BaTiO3 lead-free ceramic fibres fabricated by a powder-based extrusion method

Lead-free bismuth sodium potassium lithium titanate—barium titanate [0.885 (Bi1/2Na1/2)TiO3-0.05(Bi1/2K1/2)TiO3–0.015(Bi1/2Li1/2)TiO3-0.05BaTiO3, BNKLBT-1.5] fibres have been fabricated by a powder-based extrusion method. The ceramic fibres with 400 μ m diameter were well-crystallized after being calcined at 800°C and sintered at 1170°C. After being poled, the electromechanical coupling coefficient k33 of the fibre is 0.55 while other properties are comparable to those a ceramic disc. The BNKLNT ceramic fibres prepared by the powder-based extrusion method have good piezoelectric and ferroelectric properties and have potential to replace lead zirconate titanate (PZT) fibres in various device applications

A stepped horn transducer driven by lead-free piezoelectric ceramics

This paper presents a stepped horn transducer based on lead-free piezoelectric ceramics. A two-step titanium horn has been bonded to a Ba0.95Ti0.95Sr0.05Zr0.05O3 (BSZT) lead-free piezoelectric ceramic disk. The stepped horn is a promising candidate for transducer design mainly due to its efficacious mechanical amplification. The strontium and zirconium doped barium titanate has been prepared in disk-shape and poled in a thickness direction. When an AC voltage is applied to the electrodes of the driving disk, the lead-free piezoceramic disk produces radial ultrasonic contractions and expansions. The stepped horn transforms and amplifies the radial deformation into an axial vibration of the horn tip. At resonance, the deformation of the horn is significantly enhanced, the axial displacement of the horn tip has been measured near the resonance frequency and compared to that produced by a PZT driven transducer. Finite element modeling has been conducted to determine the vibration mode and resonance frequency of the device

Effects of MnO doping on properties of 0.97K(0.5)Na(0.5)NbO(3)-0.03(Bi0.5K0.5)TiO3 piezoelectric ceramics

MnO-doped 0.97K0.5Na0.5NbO3–0.03(Bi0.5K0.5)TiO3 lead-free piezoelectric ceramics have been fabricated by solid state reaction. The MnO-doped KNN-BKT samples show tetragonal perovskite structure and the grain size increases obviously. With an addition of the optimal doping of MnO, all the electrical properties of the samples, especially the piezoelectric and pyroelectric performance, have been enhanced significantly. The KNN-BKT ceramics, with 0.8 wt% MnO doping, exhibits optimal electrical properties: d33 = 221 pC/N, kp = 44.7%, tgδ = 1.4%, ɛr = 1229, Qm = 143, ρ = 4.464 g/cm3 and p = 221 μC/m2 K

Study of BNKLBT-1.5 lead-free ceramic/epoxy 1-3 composites

Bismuth sodium titanate based lead-free ceramic fiber with the chemical formula of 0.885 (Bi0.5Na0.5) TiO3-0.05(Bi0.5K0.5)TiO3-0.015(Bi0.5Li0.5)TiO3-0.05BaTiO3⁠, BNKLBT-1.5, has been fabricated by a powder-based extrusion method. The ceramic fibers with 400μm diameter were well crystallized after being calcined at 800°C and sintered at 1170°C⁠. The piezoelectric and ferroelectric properties of the single fiber were found to be 155pC / N and ~34.5μC / cm2⁠, respectively, which is comparable with that in bulk sample. 1-3 ceramic/polymer composites were fabricated by two routes, including dice and filled method and fiber pick-and-place method. Theoretical models were used to calculate the piezoelectric properties of the composites and compared with experimental results

Application of genetic approach for advanced planning in multi-factory environment

This paper deals with multi-factory production scheduling problems which consist of a number of factories. Each factory consists of various machines and is capable of performing various operations. Some factories may produce intermediate products and supply to other factories for assembly purpose, while some factories may produce finished products and supply to end customers. The model is subject to capacity constraints, precedence relationship, and alternative machining with different processing time. The problem encountered is to determine how to cope with each factory and machine in the system, and the objective is to minimize the makespan of a set of given jobs through proper collaboration. The makespan takes into account the processing time, transportation time between resources, and machine set-up time. This paper proposes a modified genetic algorithm to deal with the problem. The optimization reliability of the proposed algorithm has been tested by comparing it with existing approaches and simple genetic algorithms in several numerical examples found in literatures. The influence of different crossover and mutation rates on the performance of genetic search in simple genetic algorithms has also been demonstrated. The results also show the robustness of the proposed algorithm in this problem.Multi-factory production Production scheduling Assembly process Genetic algorithms Genetic parameters

Improving postponement operation in warehouse: an intelligent pick-and-pack decision-support system

Today, many manufacturers prefer to shift their pick-and-pack postponement operations to third-party logistics companies to lower operational cost and improve mass customisation flexibility. The type of pick-and-pack operation is complicated, as it usually involves a large number of stock keeping units and several warehouse operations. Surprisingly, in most 3PL, the complicated postponement operations are still mainly managed by an experienced warehouse manager, which is an unreliable methodology and often creates many mistakes. A hybrid intelligent system integrating Case-Based Reasoning and Fuzzy Logic is proposed to support the manager in making pick-and-pack postponement decisions. The system comprises a solution-refining module that proposes and holds the details of past pick-and-pack operations. This approach will be of benefit to managers as effective decision support of pick and pack planning can be provided. A case study is used to illustrate the applicability and effectiveness of the approach. Implications of the proposed approach are discussed, and suggestions for further work are outlined