Nd:YAG laser welding of stainless steel 304 for photonics device packaging

Although pulsed Nd:YAG laser welding has been widely used in microelectronics and photonics packaging industry, a full understanding of various phenomena involved is still a matter of trials and speculations. In this research, an ultra compact pulsed Nd:YAG laser with wavelength of 1.064 µm has been used to produce a spot weld on stainless steel 304. The principal objective of this research is to examine the effects of laser welding parameters such as laser beam peak powers, pulse durations, incident angles, focus point positions and number of shots on the weld dimensions: penetration depth and bead width. The ratio of the penetration depth to the bead width is considered as one of the most critical parameters to determine the weld quality. It is found that the penetration depth and bead width increase when the laser beam peak power, pulse duration and number of shot increase. In contrast, the penetration depth decreases when the laser beam defocus position and incident angle increase. This is due to the reduction of the laser beam intensity causing by the widening of the laser spot size. These experimental results provide a reference on an optimal laser welding operations for a reliable photonics device packaging. The results obtained shows that stainless steel 304 is suitable to be used as a base material for photonics device packaging employing Nd:YAG laser welding technique

The schur multiplier of pairs of nonabelian groups of order p4

Let (G,N) be a pair of groups where G is any group and N is a normal subgroup of G, then the Schur multiplier of pairs of groups is a functorial abelian group. The notion of the Schur multiplier of pairs of groups is an extension from the Schur multiplier of a group G. In this research, the Schur multiplier of pairs of finite nonabelian groups of order p4, where p is an odd prime, is determined

A cause of communication failure in managing industrialized building system (IBS) projects : a perspective view from project managers

An effective communication process is an important element in distributing information to various project teams. The previous study demonstrates the importance of communication in the project management process in order to encourage project delivery processes successfully. Unfortunately, the issue of communication still dominates Industrialization Building System (IBS) because the project development process are still based on traditional methods. This research aims to explore the cause of communication challenges between construction players in managing IBS projects. The research methodology implemented for this paper was a semi-structured interview approach used to investigate the communication problem. Five experienced project managers were chosen from across the industry. The findings of this study are valuable for improving the communication level of project teams, which will indirectly increase the level of the IBS project delivery process and strengthen team integration on IBS projects in Malaysia

An Overview of Project Delivery Methods in Construction Industry

The selection of project delivery method is one of the factors that can influence the success of a construction project. Therefore, understanding each of the primary project delivery methods used in construction industry; Design-Bid-Build (DBB), Construction Manager at Risk (CM at Risk) and Design-Build (DB) are important before the decision-making. This paper is a theory based and the objectives are to develop a new definition of project delivery method by synthesizing the existing definitions and to describe the project delivery methods aforementioned. Their advantages, disadvantages and comparison in terms of delivery phase and performance are also presented. There is no project delivery method that appropriate to be used for any construction project therefore, the development of new ideal methods is important to achieve a successful construction project

Association of vital pulp therapy outcomes with tooth type, arch location, treatment type, and number of surfaces destroyed in deciduous teeth: A retrospective study

There is a paucity of information concerning vital pulp treatment outcomes in the undergraduate teaching setting. This study aimed to determine which type of deciduous molar, arch location, type of vital pulp therapy, and the number of carious surfaces involved had a better prognosis when carried out by undergraduate dental students. The method used was the review of clinical records of 590 patients with 600 deciduous molars, that visited the outpatient undergraduate dental clinics for vital pulp therapy. Statistical analysis used to determine the associations of tooth type, arch location, treatment type, and the number of carious surfaces involved in successful outcomes was logistic regression analysis with significance set at p < 0.05. According to the regression analysis model results, there was a significant association based on tooth type (p < 0.05) and arch location (p = 0.003). In addition, there was a significant association based on the type of treatment performed (p = 0.036). However, there was no significant association in success rates based on the number of carious surfaces involved (p = 0.873). In conclusion, second deciduous molars and maxillary deciduous molars had a better overall prognosis, and indirect pulp therapy was revealed to be more highly associated with successful treatment outcomes in comparison to ferric sulfate pulpotomy in our setting

Enhancement and reproducibility of high quality factor, one-dimensional photonic crystal/photonic wire (1D PhC/PhW) microcavities

Background: The production of compact and multi-functional photonic devices has become a topic of major research activity in recent years. Devices have emerged that can be used for functional requirements in high speed optical data processing, filtering, nonlinear optical functions such as all-optical switching - and many other applications. The combination of photonic crystal (PhC) structures consisting of a single row of holes embedded in a narrow photonic wire (PhW) waveguide realised in high index-contrast materials is a possible contender for provision of a range of compact devices on a single chip. This trend has been motivated by the availability of a silicon technology that can support monolithic integration to form fully functional devices on CMOS chips. Results: We have successfully demonstrated experimentally an enhancement of the quality factor of a one-dimensional (1D) photonic crystal/photonic wire (PhC/PhW) microcavity that can exhibit resonance quality factor (Q-factor) values as high as 800,000 - together with a low modal volume of approximately 0.5 (λ/n)3. These results are based on the use of a mode matching approach previously used for device design - through the engineering of tapered hole sections within and outside the cavity - and were achieved without removing the silica cladding layer below the silicon waveguide core. The simulation results obtained in this case also agree with the experimental results obtained. Conclusions: In this work we have demonstrated that the mode matching, as light enters the photonic crystal structure, can be further enhanced through the use of careful fine tuning of the third hole, t3 of the tapered hole region outside the cavity. The Q-factor value obtained was approximately four times greater than that achieved in our previous work on a similar structure

Construction Firm Readiness towards Implementing Integrated Project Delivery (IPD)

The Malaysian government has taken the initiative of implementing Industrialised Building System (IBS) in which components are manufactured in mass production under a controlled environment (on or off site), transported, positioned and assembled into a structure with minimal additional site works. It is hope that IBS can improve the performance of construction industry. However, one of the main barriers in Malaysian IBS implementation is lack of integration among stakeholder involved during the project delivery stage. In order to overcome this barrier, a new collaborative procurement or project delivery namely as Integrated Project Delivery (IPD) which is using a multi-party contract (more than two parties selected) has been introduced. Integrated Project Delivery (IPD) is defined as a project delivery approach that integrates people, systems, business structures and practices into a process that collaboratively harnesses the talents and insights of all project participants to optimise the results, increase value to the owner, reduce waste, and maximize efficiency through all phases of design, fabrication and construction. Although, many researchers have argue the importance of IPD in project delivery process, but the readiness of construction industries must be established. This research has used a quantitative research process that involved a few phases including literature review stage, data collection stage, framework development stage, validation and recommendation stage. This research is to obtain data based on multidisciplinary IBS stakeholders perspectives, respondent include project managers, resident engineers, architects and contractors are among the potential candidates. Respondents that directly involved in the construction industry mentioned that their firms are willing to change and implement IPD. The firms readiness recorded at the moderate mean value. It can be noted that each firm involved as respondents are ready to implement

Optimisation of paint removal operation using waterjet cleaning process

The need of cleaning automotive paint without secondary pollution has recently become a major concern globally. The waterjet technology has extended its application to include surface treatment, machining, cleaning and cutting of materials. Plain waterjet is frequently used for cleaning since its offers environmentally friendly concept which results near zero pollution to the surroundings. This research aims to analyse and optimise the use of multiple passes in waterjet cleaning process for removal of automotive paint using response surface method (RSM). The effect of surface roughness (Ra) and its topography were analysed. RSM, analysis of variance (ANOVA), fractional factorial at two levels were utilized to optimize the plain waterjet process parameters for effective cleaning of paint. It was found that the lateral feed and pressure were the most significant control factors in influencing the cleaning performance criteria. Mathematical model was developed using linear regression analysis to predict the surface roughness in terms of cleaning parameters of plain waterjet process. The model had successfully predicted the Ra of the plain waterjet cleaned automotive parts within the limit of this study. The recommended optimal parametric combinations for better Ra were found to be waterjet pressure of 34.0 MPa, traverse rate of 500 mm/min, standoff distance of 10 mm, number of passes of 1 and lateral feed of 0.6 mm

Investigation on the effect of multiple passes in plain waterjet cleaning of paint

Paint removal process in automotive coating is widely used in vehicle component recycling industry. The need of utilization and recycling the automotive component without producing secondary pollution from the paint removal process is recently become a major concern globally. Water jet cleaning is a new method for paint removal and getting recognition because of environmental friendly and it is better than mechanical cleaning such as sand blasting, brushing with water, hydropneumatic cleaning, controlled dry sanding, low pressure water projection and low pressure water spray. The present study focuses on the investigation of effect of multiple passes in plain water jet cleaning on paint removal process. A new method of multiple passes treatment is applied in plain water jet cleaning to access its effect on surface roughness and paint removal rate. It was found that, with increasing of number of passes, the surface roughness and paint removal rate is slightly increase. It is also found that the increase in water jet pressure will increase the surface roughness and paint removal rate. This is probably because increasing pressure will leads to more energy to remove the paint. It is found also that the increase in traverse rate increase the surface roughness and decrease paint removal rate. Based on the present study, it is a high prospect to apply multiple passes of paint removal using plain water jet in automotive industry