Evaluation and derivation of process plans in turning

The objective of this paper is to formalize process planning selection to minimise the total processing time and the total number of processing steps. The study is performed by defining the processes and part description for turned parts. Two examples solved by the two proposed methods are reported. One of them is the derivation of a new plan which can be expressed as a function of the generated plans. The second method is based on the combination of process plans to generate a new plan which conforms optimally to the change in specification.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45881/1/170_2005_Article_BF01351320.pd

Genetic Algorithm Optimization Model for Determining the Probability of Failure on Demand of the Safety Instrumented System

A more accurate determination for the Probability of Failure on Demand (PFD) of the Safety Instrumented System (SIS) contributes to more SIS realiability, thereby ensuring more safety and lower cost. IEC 61508 and ISA TR.84.02 provide the PFD detemination formulas. However, these formulas suffer from an uncertaity issue due to the inclusion of uncertainty sources, which, including high redundant systems architectures, cannot be assessed, have perfect proof test assumption, and are neglegted in partial stroke testing (PST) of impact on the system PFD. On the other hand, determining the values of PFD variables to achieve the target risk reduction involves daunting efforts and consumes time. This paper proposes a new approach for system PFD determination and PFD variables optimization that contributes to reduce the uncertainty problem. A higher redundant system can be assessed by generalizing the PFD formula into KooN architecture without neglecting the diagnostic coverage factor (DC) and common cause failures (CCF). In order to simulate the proof test effectiveness, the Proof Test Coverage (PTC) factor has been incorporated into the formula. Additionally, the system PFD value has been improved by incorporating PST for the final control element into the formula. The new developed formula is modelled using the Genetic Algorithm (GA) artificial technique. The GA model saves time and effort to examine system PFD and estimate near optimal values for PFD variables. The proposed model has been applicated on SIS design for crude oil test separator using MATLAB. The comparison between the proposed model and PFD formulas provided by IEC 61508 and ISA TR.84.02 showed that the proposed GA model can assess any system structure and simulate industrial reality. Furthermore, the cost and associated implementation testing activities are reduced

Part programming and process planning within computer aided manufacture

Imperial Users onl

Surface quality of marble machined by abrasive water jet

This paper presents a study conducted to examine the effect of cutting parameters, namely standoff distance, nozzle traverse speed (TS), abrasive flow rate (AFR), and material type on cutting performance for two types of marble workpieces, Carrara white and Indian green. Statistical analysis was undertaken to assess the influence of the cutting parameters on the process performances in terms of surface roughness, surface waviness, and Kerf taper ratio. The results showed that the TS and material type were the most significant factors that affected surface roughness and Kerf taper ratio. Also, although AFR was found to have significant effect on surface waviness, it had no noticeable influence on surface roughness nor Kerf taper ratio

On Convergence of Intermediate Order Statistics under Power Normalization

We discuss the convergence of the moments of intermediate order statistics under power normalization. The moments convergence is established for four p-max-stable laws according to conditions imposed on the considered distribution and on the rank sequence

Statistical optimization, characterization, antioxidant and antibacterial properties of silver nanoparticle biosynthesized by saw palmetto seed phenolic extract

Abstract On the global market, silver nanoparticles (Ag-NPs) are in high demand for their various applications in biomedicine, material engineering, and consumer products. This study highlighted the biosynthesis of the Ag-NPs using saw palmetto seed phenolic extract (SPS-phenolic extract), which contained vital antioxidant-phenolic compounds. Herein, central composite statistical design, response surface methodology, and sixteen runs were conducted to optimize Ag-NPs biosynthesis conditions for maximizing the production of Ag-NPs and their phenolic content. The best-produced SPS-Ag-NPs showed a surface plasmon resonance peak at 460 nm and nano-spherical sizes ranging from 11.17 to 38.32 nm using the UV spectrum analysis and TEM images, respectively. The produced SPS-Ag-NPs displayed a high negative zeta-potential value (− 32.8 mV) demonstrating their high stability. The FTIR analysis demonstrated that SPS-phenolic compounds were involved in sliver bio-reduction and in stabilizing, capping, and preventing Ag-NP aggregation. The thermogravimetric investigation revealed that the produced SPS-Ag-NPs have remarkable thermal stability. The produced SPS-Ag-NP exceeded total antioxidant activity (13.8 µmol Trolox equivalent) more than the SPS-phenolic extract (12.0 µmol Trolox equivalent). The biosynthesized SPS-Ag-NPs exhibited noticeably better antibacterial activity against multidrug-resistant Gram-negative E. coli and Gram-positive S. aureus compared to SPS-phenolic extract. Hence, the bio-synthesized SPS-Ag-NPs demonstrated great potential for use in biomedical and antimicrobial applications

Common Eye Diseases in Children in Saudi Arabia (Jazan)

Background The rise in childhood eye diseases has become a matter of concern in Saudi Arabia, and hence a study has been conducted on the residents of Jazan. The aim of the research was to find out the root cause of such issues and provide a solution to prevent such circumstances for it may affect the vision of children. In this study, therefore, we aimed to determine the types of childhood eye diseases in Jazan and to discuss the best ways to prevent them or prevent their effect on the vision of our children. Our institutions are working toward the longevity and welfare of the residents, and healthcare is one of the important aspects in such a field. Methods This is a retrospective review of all patients less than 18 years of age who presented to the pediatric ophthalmology clinic of Prince Mohammed Bin Nasser Hospital, Jazan, between October 2014 and October 2015. The data, collected on 385 cases, included the age at first presentation, sex, clinical diagnosis, refractive error (RE) if present, and whether the child had amblyopia. If the child did not undergo complete ophthalmic examination with cycloplegic refraction, he/she was excluded. All data were collected and analyzed using the software SPSS. A P -value < 0.05 was considered statistically significant. Results We reviewed the files of 385 children, with a male/female ratio of 1.1:1.0. The group aged 0–6 years made up the largest group ( P = 0.01), and the ratio is an expression to define the credibility of the study using a chi-squared test. Strabismus (36.9%), RE (26.5%), ocular trauma (7.5%), infection of cornea and conjunctiva (7.3%), and keratoconus (6.2%) were the most common conditions. There was no significant difference in presentation by age group and sex among children with REs and squint. Trauma was seen more commonly among males and in the group aged 12–18 years. Conclusion In this retrospective study, the focus was on the common childhood eye diseases that were considerably high. Hypermetropia was the predominant RE, which is in contrast to other studies where myopia was more common. However, it is important to promote public education on the significance of early detection of strabismus, REs, and amblyopia and have periodic screening in schools. The discussion of the various issues is aimed at increasing the awareness and building a support for the cause by creating the knowledge base to treat things on time and acknowledging the severity of the issues

Purification and characterization of cysteine protease of Sarcocystis fusiformis from infected Egyptian water buffaloes

Abstract Sarcocystis spp. infects water buffaloes (Bubalus bubalis) causing sarcocystosis. In the present study, Sarcocystis fusiformis was recognized in Egyptian water buffaloes based on histological observation and molecular analysis of internal transcribed spacer 1 (ITS1), 18S ribosomal RNA (18S rRNA) and cytochrome c oxidase subunit I (COX-1) gene fragments. Chemotherapy and vaccines against Sarcocystis spp. could potentially target proteases because they may play a crucial role in the infection. Cysteine proteases are multifunctional enzymes involved in vital metabolic processes. However, the involvement of proteases in S. fusiform infection has not yet been characterized. Here, the purification and study on some biochemical properties of protease isolated from cysts of S. fusiform were carried out. Protease with a molecular weight of 100 kDa was purified. LC–MS/MS analyzed the protein sequence of purified protease and the data suggested that the enzyme might be related to the cysteine protease. The purified protease exhibited maximum activity at pH 6 and a temperature of 50 °C. The Michaelis–Menten constant (Km), the maximum velocity (Vmax), and the turnover number (Kcat) were determined. The complete inhibition effect of cysteine inhibitors indicated that the purified enzyme is a cysteine protease. The results suggested that S. fusiform proteolytic enzyme may be necessary for parasite survival in water buffaloes by digesting host tissues. Therefore, cysteine protease could be a suitable target for vaccinations