Computer aided process planning for multi-axis CNC machining using feature free polygonal CAD models

This dissertation provides new methods for the general area of Computer Aided Process Planning, often referred to as CAPP. It specifically focuses on 3 challenging problems in the area of multi-axis CNC machining process using feature free polygonal CAD models. The first research problem involves a new method for the rapid machining of Multi-Surface Parts. These types of parts typically have different requirements for each surface, for example, surface finish, accuracy, or functionality. The CAPP algorithms developed for this problem ensure the complete rapid machining of multi surface parts by providing better setup orientations to machine each surface. The second research problem is related to a new method for discrete multi-axis CNC machining of part models using feature free polygonal CAD models. This problem specifically considers a generic 3-axis CNC machining process for which CAPP algorithms are developed. These algorithms allow the rapid machining of a wide variety of parts with higher geometric accuracy by enabling access to visible surfaces through the choice of appropriate machine tool configurations (i.e. number of axes). The third research problem addresses challenges with geometric singularities that can occur when 2D slice models are used in process planning. The conversion from CAD to slice model results in the loss of model surface information, the consequence of which could be suboptimal or incorrect process planning. The algorithms developed here facilitate transfer of complete surface geometry information from CAD to slice models. The work of this dissertation will aid in developing the next generation of CAPP tools and result in lower cost and more accurately machined components

Process planning for the rapid machining of custom bone implants

This thesis proposes a new process planning methodology for rapid machining of bone implants with customized surface characteristics. Bone implants are used in patients to replace voids in the fractured bones created during accident or trauma. Use of bone implants allow better fracture healing in the patients and restore the original bone strength. The manufacturing process used for creating bone implants in this thesis is highly automated CNC-RP invented at Rapid Manufacturing and Prototyping Lab (RMPL) at Iowa State University. CNC-RP is a 4th axis rapid machining process where the part is machined using cylindrical stock fixed between two opposing chucks. In addition to conventional 3 axes, the chucks provide 4th rotary axis that allows automated fixturing setups for machining the part. The process planning steps for CNC-RP therefore includes calculating minimum number of setup orientations required to create the part about the rotary axis. The algorithms developed in this thesis work towards calculating a minimum number of orientations required to create bone implant with their respective surface characteristics. Usually bone implants may have up to 3 types of surfaces (articular/periosteal/fractured) with (high/medium/low) finish. Currently CNC-RP is capable of creating accurate bone implants from different clinically relevant materials with same surface finish on all of the implant surfaces. However in order to enhance the functionality of the bone implants in the biological environment, it is usually advisable to create implant surfaces with their respective characteristics. This can be achieved by using setup orientations that would generally isolate implant surfaces and machine them with individual finishes. This thesis therefore focuses on developing process planning algorithms for calculating minimum number of orientations required to create customized implant surfaces and control related issues. The bone implants created using new customization algorithms would have enhanced functionality. This would reduce the fracture healing time for the patient and restore the original bone strength. The software package created using new algorithms will be termed as CNC-RPbio throughout in this thesis The three main tasks in this thesis are a) calculating setup orientations in a specific sequence for implant surfaces b) Algorithms for calculating a minimum number of setup orientations to create implant surfaces c) Machining operation sequence. These three research tasks are explained in details in chapter 4 of this thesis. The layout of this thesis is as follows. Chapter 1 provides introduction, background and motivation to the research in this thesis. Chapter 2 provides a literature review explaining different researches conducted to study the effects of different surface finish on the bone implants on their functionality. It also presents different non-traditional and RP techniques used to create bone implant geometries with customized surfaces, their advantages and limitations. Chapter 3 gives the overview of process planning algorithms used for CNC-RP and those needed for CNC-RPbio. Chapter 4 is the main chapter of the thesis including process planning algorithms for rapid machining of bone implants with customized surfaces using CNC-RP in details, while Chapter 5 provides Conclusions and Future work

Recognition of Marathi Newsprint Text Using Neural Network and Genetic Algorithm

Now a day there are many new methodologies required for the increasing needs in newly emerging areas, with this methodologies there are many techniques are present for the character recognition of handprint Devanagri, Bengali, Tamil, China etc. But very little research is for printed material. So in our project we propose the recognition of devnagari printed text using neural network and genetic algorithm. In India, more than 300 million people use Devanagari script for documentation. There has been a significant improvement in the research related to the recognition of printed as well as handwritten Devanagari text in the past few years.. All feature-extraction techniques as well as training, classification and matching techniques useful for the recognition are discussed in various sections of the paper. An attempt is made to address the most important results reported so far and it is also tried to highlight the beneficial directions of the research till date. Moreover, the paper also contains a comprehensive bibliography of many selected papers appeared in reputed journals and conference proceedings as an aid for the researchers working in the field of Devanagari printed text using neural network and genetic algorithm. DOI: 10.17762/ijritcc2321-8169.160411

Duxorubicin-induced cardiotoxicity

The survival rate of cancer patients has greatly increased over the last 20 years. However, to achieve this result, a considerable price has been paid in terms of the side-effects associated with the intensive anticancer treatment. Cardiotoxicity of anticancer drugs is a serious problem. It is defined, by the National Cancer Institute, as the “toxicity that affects the heart.” This definition not only includes a direct effect of the drug on the heart, but also an indirect effect due to enhancement of hemodynamic flow alterations or due to thrombotic events. Cardiotoxicity can develop in a subacute, acute, or chronic manner. The risk for such effects depends upon: cumulative dose, rate of drug administration, mediastinal radiation, advanced age, younger age, female gender, pre-existing heart disease and hypertension. Anthracyclines, such as doxorubicin (DOX), cause serious cardiac side-effects. Acute tachyarrhythmias and acute heart failure (HF) may occur after high doses, but these reactions are now rare due to changed dosage schemes (e.g. slower infusion) with the aim to prevent this. However, the sub-acute or chronic cardiac effects of anthracyclines remain a clinical problem. Clinically, anthracycline induced cardiotoxicity manifests itself as left ventricular failure, which develops insidiously over months to years after completion of the anthracycline based chemotherapy and may result in congestive HF. The mechanism of anthracyclin induced cardiotoxicity is not totally unraveled. It is likely that the decline in myocardial function is related to apoptosis of cardiac myocytes that occurs apparently at random in the myocardium. Anthracyclin induced formation of reactive oxygen species (ROS) in the presence of intracellular iron, impaired homeostasis of intracellular iron and calcium (that may facilitate the apoptosis induced by the ROS) have been put forward as mechanisms. Cardiac protection can be achieved by limitation of the cumulative dose. Further, addition of the antioxidant and iron chelator dexrazoxane to anthracycline therapy has shown to be effective in lowering the incidence of anthracycline induced cardiotoxicity

Comparison of Fissure Healing and The Incidence of Headache Among the Patients Treated with Endo- and Perianal Application of 0.2% Glyceryl Trinitrate for Chronic Anal Fissure

Introduction: Chronic anal fissure is associated with significant morbidity and reduction in quality of life mostly in young healthy adults. Glyceryl Trinitrate, a most commonly used agent for treatment, is associated with incidence of headache causing discontinuation of treatment. There is belief that endoanal application instead of perianal is associated with lower incidence of headache. This study is to compare the incidence and severity of headache in between perianal and endoanal application of GTN ointment. Methods: Thirty patients were taken in each perianal and endoanal group. They were given orientation to apply 375gm of ointment either endoanally or perianally and to record severity of headache according to visual analogue scale. This record was noted by independent observer in telephonic conversation. Patients were followed up at 6 weeks for evaluation fissure. Results: The mean age, male female ratio and features of chronicity was similar in both the group however the duration of symptoms between the group was different. Regarding outcome, Overall incidence of headache was seen in two-third of patient with severe headache in approx. 10%. Severity of headache was slightly lower in endoanal group but the difference was not significant. Healing rate was comparable. Two patient in perianal and 3 in endoanal group were lost for follow up.  Conclusions: Endoanal application of GTN ointment is associated with slight decrease in intensity of headache and is comparable with perianal application for fissure healing.  Keywords: anal fissure; endoanal; glyceryl trinitrate;headache; perianal.| PubMe

Increased growth temperature and vitamin B12 supplementation reduces the lag time for rapid pathogen identification in BHI agar and blood cultures [version 2; peer review: 2 approved]

Background: Rapid diagnostics of pathogens is essential to prescribe appropriate antibiotic therapy. The current methods for pathogen detection require the bacteria to grow in a culture medium, which is time-consuming. This increases the mortality rate and global burden of antimicrobial resistance. Culture-free detection methods are still under development and are not common in the clinical routine. Therefore, decreasing the culture time for accurately detecting infection and resistance is vital for diagnosis. Methods: This study investigated easy-to-implement factors (in a minimal laboratory set-up), including inoculum size, incubation temperature, and additional supplementation (e.g., vitamin B12 and trace metals), that can significantly reduce the bacterial lag time (tlag). These factors were arranged in simple two-level factorial designs using Gram-positive cocci (Staphylococcus aureus), Gram-positive bacilli (Bacillus subtilis), and Gram-negative bacilli (Escherichia coli and Pseudomonas aeruginosa) bacteria, including clinical isolates with known antimicrobial resistance profiles. Blood samples spiked with a clinical isolate of E. coli CCUG 17620 (Culture Collection University of Gothenburg) were also tested to see the effect of elevated incubation temperature on bacterial growth in blood cultures. Results: We observed that increased incubation temperature (42°C) along with vitamin B12 supplementation significantly reduced the tlag (10 – 115 minutes or 4% - 49%) in pure clinical isolates and blood samples spiked with E. coli CCUG17620. In the case of the blood sample, PCR results also detected bacterial DNA after only 3h of incubation and at three times the CFU/mL. Conclusion: Enrichment of bacterial culture media with growth supplements such as vitamin B12 and increased incubation temperature can be a cheap and rapid method for the early detection of pathogens. This proof-of-concept study is restricted to a few bacterial strains and growth conditions. In the future, the effect of other growth conditions and difficult-to-culture bacteria should be explored to shorten the lag phase

Pre-operative Prediction of Difficult Laparoscopic Cholecystectomy

Introduction: Laparoscopic cholecystectomy is one of the most common operation performed. Though LC have become safer and easier at times it can be difficult. Difficult cases can result in prolonged operative time, bleeding, bile spillage, conversion to open technique and bile duct injury resulting in unplanned prolonged hospital stay, increase in estimated cost to the patients and for the surgeon it leads to increased stress during operation and time pressure to complete the operative list. . Identification of difficult cases has potential advantages for surgeons, patients and their relatives. We aim to develop and validate a scoring system to predict difficult LC preoperatively. Methods: Prospective study. History, physical examination, abdominal ultrasound and biochemical parameters were included to develop a scoring system. Hundred patients undergoing LC were included and preoperative scores were calculated preoperatively to predict difficult LC which was compared with operative assessment. Results: Sensitivity and specificity of the preoperative scoring for difficult case was 53.8 % and 89.2 % respectively with PPV of 63.64 % and NPV of 84.62%. Only three parameters (history of acute cholecystitis, gall bladder wall thickness and contracted gall bladder) were statistically significant to predict difficult LC individually. Area under ROC curve was 0.779 (95 % CI, 0.657-0.883). Conclusions: Preoperative scoring system can be used to predict difficult LC. Surgeons can plan operation based on predicted difficulty. Patients and relatives can be counselled preoperatively for the possibility of difficult operation, prolonged hospital stay and increased cost in predicted difficult case. Keywords: difficult cholecystectomy; laparoscopic cholecystectomy; symptomatic cholelithiasis