Search results

This paper aims to present a new design for removable partial dentures (RPDs) for partially edentulous patients to improve the efficiency and quality of RPD manufacturing. Additive and subtractive manufacturing technologies and zirconium silicate micro-ceramic bonding in the aesthetic zone are used herein.

A case was presented. First, RPD digital definitive casts were acquired, and then digital frameworks with crown retainers and digital crowns were obtained by computer-aided design (CAD). The titanium alloy frameworks and resin crowns were fabricated by three-dimensional (3D) printing and computer-aided manufacturing (CAM) processes, respectively. The crowns adhered to the crown retainers. Ceramage bonding was used to reform the gingival anatomy in the aesthetic zone during the fabrication of the RPDs. The finished RPDs were assessed by a clinician and delivered to the patient.

The RPDs were conventionally assessed by a clinician, were deemed to be accurate and satisfied both the patient and clinician.

This novel method provides a way to fabricate RPDs with a combination of additive and subtractive manufacturing technologies. The design of the framework was different from that of a conventional framework because it contained the crown retainers, and the traditional base retainer no longer existed. Ceramage bonding was used to replicate the gingival anatomy in the aesthetic zone. The new RPDs provided accuracy and were less time-consuming to produce than those produced with the traditional method. The new method enables the digital manufacturing of nearly the entire RPDs.

A novel Ka-band compact parallel-coupled microstrip bandpass filter with harmonic suppression performance has been designed, implemented and tested on GaAs MMIC.

This proposed filter consists of modified coupled-line units with T-shaped open-stubs.

The proposed filter with T-shaped open-stubs is valuable in performance with low loss at fundamental frequency, suppression at harmonic frequencies and small size. The simulation is based on full-wave electromagnetic analysis and the measurement is based on chip test. It shows an insertion loss below 1.2 dB, return loss better than 20 dB in the pass band and high than 28 dB suppression at harmonic frequencies.

This Ka-band MMIC filter with harmonic suppression is attractive for the millimeter-wave system.

This study aims to investigate the several parameters in wafer-level packaging (WLP) to find the most critical factor impacting the thermal fatigue life, such as the height of copper post, the height of solder bump, the thickness of chip. The FEA results indicate the height of solder bumps is the most important factor in the whole structure.

The copper post bumps with 65 µm pitch are proposed to investigate the thermal-mechanical performance of WLP. The thermal cycle simulation is used to evaluate the reliability of WLP by using finite element analysis (FEA). Taguchi method is adopted to obtain the sensitivity of parameters of three-dimension finite element model, for an optimized configuration.

It can be found that the optimal design has increased thermal fatigue life by 147% compared with the original one.

It is concluded that the finite element simulation results show outstanding thermal-mechanical performances of the proposed 65 µm pitch copper post bumps of WLP, including low plastic strain, high thermal fatigue life, which are desired for mobile device.

Exploring the antecedents of members community participation is extremely important for virtual communities (VCs) research and practice. As an important social characteristic of individuals, social embeddedness has been proved as an important antecedent of many individual behaviors; however, few research has investigated the influence of virtual community members social embeddedness on virtual community members’ participation. To fill this gap, the purpose of this paper is to explore the relationship between social embeddedness and community participation in VCs.

This paper conducted empirical study to test the hypotheses. Based on existing scales, this research designed the questionnaire and used a web-based survey to collect the data from VCs in China. To avoid the common method bias, this study collected data at two different times. The final sample included 96 virtual community members from seven communities (community size ranging from 10 to 25) of Baidu Tieba, which is the largest Chinese online communication platform. And this paper used regression models to analysis the data.

Based on social network theory, this paper found that virtual community members’ social embeddedness in their virtual community has a curvilinear (i.e. inverted U-shaped) effect on their community participation behaviors. And members’ perceived autonomy mediates the curvilinear (i.e. reversed U-shaped) relationship between social network embeddedness and community participation. Furthermore, member instability moderates the curvilinear (i.e. inverted U-shaped) main effect, such that the curvilinear relationship is weakened when member instability is high.

Departing from previous virtual community studies that examine antecedences of participation in linear logic, this study applied social network theory to create a complex, curvilinear, moderated mediation model. The result reveals a curvilinear (i.e. inverted U-shaped) relationship between virtual community members’ social embeddedness in the virtual community and their community participation. And this study also introduce autonomy as mediator and member instability as moderator. By testing the whole model between community members’ social embeddedness and community participation, this study contributes to deepen the understanding of social embeddedness and virtual community participation.

The purpose of this paper is to present a K-band modified hairpin bandpass filter on a planar circuit with harmonic suppression and compact size.

The inter-connect transmission lines of conventional hairpin filter are replayed by T-shaped open stub to achieve transmission zero for second harmonic. This filter is simulated and optimized by using electromagnetic simulation software and tested on-chip.

This proposed filter shows the return loss of better than −10dB, the insertion loss of better than 2 dB in pass-band and suppression of more than 40 dB at second harmonic.

The proposed filter can be designed on monolithic microwave integrated circuit, PCB or LTCC and it is useable for microwave and microwave and millimeter-wave systems.

The purpose of this paper is to explore an application of computer‐aided design and manufacture (CAD/CAM) to a process of electronically surveying a scanned dental cast as a prior stage to producing a sacrificial pattern for a removable partial denture (RPD) metal alloy framework.

With the introduction of laser scan technology and commercial reverse engineering software, a standard plaster maxillary dental cast with dentition defect was successfully scanned and created as a STL‐formatted digital cast. With the software, the unwanted undercuts were eliminated based on the desired path of insertion. Parts of the RPD framework were then successfully custom‐designed and combined as a whole.

A sacrificial pattern was produced by rapid prototyping (RP) method and finally casted with chromium cobalt alloy. With suitable finishing process, both the sacrificial pattern and the casted framework fitted the cast well.

The research indicated the feasibility of creating a library of RPD framework components. It is believed that, in the future, with the advance of the techniques, a totally new platform can be developed for the design and fabrication of custom‐fit RPD framework based on the CAD/CAM/RP system.

This paper aims to improve the efficiency and the quality of metal dental prostheses, reporting on the first patient‐fitted titanium (Ti) complete denture base plate fabricated by integrating the technologies of computer‐aided design and computer‐aided manufacture (CAD/CAM) and laser rapid forming (LRF).

To make a complete Ti denture base plate, the traditional lost‐wax‐casting technique is commonly used in dentistry. In order to simplify this labor‐intensive process, a new method combined with LRF was invented. Initially, a maxillary edentulous plaster cast was converted to point cloud data by laser scanning system. Subsequently, point cloud data were reconstructed into a 3D solid digital cast, which is stored in standard triangulation language format. Thereafter the 3D denture base was sliced electronically into a sequence of layers defining the regions of the component and, based on it, the complete Ti denture base plate was built layer‐by‐layer using a laser additive manufacturing technology.

After CAD/CAM/LRF process, the Ti denture base plate was designed and successfully fabricated layer‐by‐layer. After the traditional dental finishing techniques, the complete Ti denture base plate was made and assessed by clinician and patient. The clinical evaluation on quality of fit was judged to be acceptable.

The CAD/CAM/LRF system is a potential candidate to replace the traditional lost‐wax‐casting technique and provides a new platform for the design and manufacturing of custom‐made Ti denture plates and other restorations especially for implant substructure and framework of partial removal of denture.

The purpose of this paper is to present the research on the effect of the shielding box to the dispersion properties of the microstrip lines, obtained by both theory analysis and the experimental test. Additionally, some principles about the effect of the shielding box are given, which could provide some useful information for the design of monolithic microwave integrated circuits.

The dispersion of the shielded microstrip line is analysis by the MOL. The measured data are obtained by using vector network analyzer and the calibration method is through, reflect, line. The structure of the test fixtures will also be illustrated in this paper.

The size of the shielding box has a great impact on the dispersion properties of the microstrip lines. The shielding box will lead to the decrease of the effective dielectric constant of the shielded microstrip lines. The effects of shielding box have a big relation to the ratio of the size of the shielding box to the size of the microstrip lines. When this ratio becomes bigger, the effects will decrease and can even be ignored completely.

This paper presents the effects of the shielding box on the dispersion properties of the microstrip lines. Both the measured results and the theory analysis are given in a wide‐frequency range and the structures of the test fixture are also illustrated in detail.

The purpose of this paper is to study and discuss the effects of the finite metallisation thickness and conductivity on the properties of microstrip lines.

Effective dielectric constant and attenuation constant of microstrip lines with finite metallization thickness and finite conductivity are analyzed by the method of lines. The experimental results are obtained by using Vector Network Analyzer and the 3680 V Universal Test Fixture of Anritsu.

The strip thickness has a great impact on the attenuation constant of the microstrip lines. The effects can be divided into three parts by the relationship between strip thickness (t) and skindepth (δ). When t<δ, the attenuation constant will decrease rapidly as the strip thickness increase. When δ < t<2δ, the attenuation constant still decrease rapidly as the strip thickness increase, but the slope of the curve will be smaller. When 2δ < t, the effects of the strip thickness will become insignificant and the attenuation constant still decrease slowly as the strip thickness increase.

This paper presents some useful principles about the effects of the finite metallization thickness and finite conductivity in microstrip lines. The reasons for these effects are discussed by analyzing the longitudinal electric field distribution in the strip. Finally, some experimental results are given to verify these principles.

This paper aims to investigate, in China stock market, whether the reputation loss of a firm caused by financial restatements will lead to significant economic consequences such as financial distress and how a firm should respond to such a crisis.

This paper uses Chinese A-share listed firms from 2004 to 2013 as research samples to test research hypotheses using regression analyses.

This paper finds a significant relationship between restatements and financial distress, and such a relationship will be affected by both the type and the magnitude of restatements. More importantly, we find joint effects of restatements and state ownership on financial distress, which provides a unique contribution to the extant literature in restatement, financial distress and crisis management using Chinese stock markets data. It shows that ownership structure, affecting the firm reputation and crisis responses strategies, plays a significant role in consequences of restatements, and it is more important for state-owned enterprises (SOEs) to undertake an appropriate crisis response strategy to reduce the negative impact of restatements.

The results suggest that the damage to a firm’s reputation caused by restatements is affected by restatement type and state ownership. To reduce the negative consequences and avoid financial distress, firms should consider both the restatement type and their firm characteristics when deciding different actions to respond to restatements. In particular, SOEs should act in a more timely manner and take reputation-rebuilding actions such as taking the responsibility and making apologies and taking prompt remedial actions after restatements to regain the public trust and avoid more serious economic consequences. The Chinese government should strengthen their supervisions of SOEs and put more effort to help SOEs reduce administrative procedures, and to improve the efficiency of the implementation of recovery plans after restatements to reinstate firm credibility.

First, this paper is among the first to link financial restatement, including the type and magnitude of restatements, with financial distress, and the authors find a significant relationship between restatement type and financial distress in China stock markets. Second, this paper is the first to examine whether there is a joint effect of state ownership and restatements on financial distress. Third, this study examines how the magnitude and pervasiveness of restatements influence financial distress and find that both result in an increase of financial distress. Finally, this paper is among the first to connect crisis management and accounting literature to explain how a reputation loss caused by financial restatement may damage a firm’s value and subsequent performance, and based on which to suggest crisis-responses strategies.