Laser-assisted mechanical micromachining (LAMM) is a micro-cutting method that employs highly localized thermal softening of the material by continuous wave laser irradiation focused in front of a ...miniature cutting tool. However, since it is a heat-assisted process, it can induce a detrimental heat-affected zone (HAZ) in the part. This paper focuses on characterization and prediction of the HAZ produced in a LAMM-based micro-grooving process. The heat-affected zone generated by laser heating of H-13 mold steel (42 HRC) at different laser scanning speeds is analyzed for changes in microstructure and microhardness. A 3-D transient finite element model for a moving Gaussian laser heat source is developed to predict the temperature distribution in the workpiece material. The model prediction error is found to be in the 5–15% range with most values falling within 10% of the measured temperatures. The predicted temperature distribution is correlated with the HAZ and a critical temperature range (840–890
°C) corresponding to the maximum depth of the HAZ is identified using a combination of metallography, hardness testing, and thermal modeling.
Cooling and lubrication are very critical to ensure workpiece quality in grinding due to the high friction and intense heat generation involved in the process. Liquid lubricants have traditionally ...been used in flood form or minimum quantity lubrication (MQL), raising however, major environmental and economic concerns. The focus of this study is to evaluate the performance of graphite nanoplatelets as a lubricant in surface grinding. The role of graphite's characteristics such as form, size and concentration; and the effect of the carrying medium and the graphite's application method are determined based on an experimental study. The results indicate that graphite nanoplatelets significantly reduce the grinding forces, specific energy, and improve surface finish during surface grinding of hardened D-2 tool steel. A comparison with results obtained in conventional MQL grinding is also provided. The proper selection of graphite, carrying medium and application method can lead to a low cost, nontoxic and simple alternative to solid lubrication or MQL grinding.
Vibration monitoring is a critical aspect of assessing the health and performance of machinery and industrial processes. This study explores the application of machine learning techniques, ...specifically the Random Forest (RF) classification model, to predict and classify chatter—a detrimental self-excited vibration phenomenon—during machining operations. While sophisticated methods have been employed to address chatter, this research investigates the efficacy of a novel approach to an RF model. The study leverages simulated vibration data, bypassing resource-intensive real-world data collection, to develop a versatile chatter detection model applicable across diverse machining configurations. The feature extraction process combines time-series features and Fast Fourier Transform (FFT) data features, streamlining the model while addressing challenges posed by feature selection. By focusing on the RF model’s simplicity and efficiency, this research advances chatter detection techniques, offering a practical tool with improved generalizability, computational efficiency, and ease of interpretation. The study demonstrates that innovation can reside in simplicity, opening avenues for wider applicability and accelerated progress in the machining industry.
Machining chatter is a phenomenon resulting from self-oscillation between a machining tool and workpiece. This self-oscillation results in variation on the machined product that reduces the ability ...to meet desired specifications. Chatter is a widely studied topic as it directly relates to the quality of machined products. This study details the application of a Random Forest (RF) classifier with Recursive Feature Elimination (RFE) to machining audio collected by a single microphone during down-milling operations. This approach allows straightforward feature elimination that results in an easily understood set of analyzed dimensions. Stability is predicted solely based on the classification output of the RF classifier. Our approach proves highly predictive with consistent machining setup and a small sample set. We also review transferability between machining setups and present key findings. Our RF approach demonstrates the ability to analyze and classify chatter through a low-cost approach with limited training data required. The motivation for using a single microphone is to enable detection on machines without other sensors, such as accelerometers, present in the machining setup. The value of the in-process sensor and chatter classifier is highlighted because the machining setup included asymmetric dynamics that reduced the accuracy of the traditional analytical stability solution. We see a natural progression to deploying this audio-only methodology with real-time processing and classification using either a laptop or smartphone. This progression will allow visual indicators during the machining process that can alert machinists of progression into unstable machining processes.
Tzipi Livni, the Israeli Foreign Minister, said Israel will release more than US$500-million in Palestinian tax and customs revenues it is holding once it receives assurances Mr. Mahmoud Abbas's new ...emergency government is committed to peace and recognizes Israel's existence. The restoration of the funding means about US$126-million, including US$86-million for reform of Palestinian security forces and US$40-million via the UN Relief and Works Agency, will begin flowing to Mr. Abbas's government, operating out of the West Bank. The resumption of political ties is intended to isolate Hamas and strengthen Mr. Abbas's Fatah. But despite the boost from the United States and the European Union, it's unlikely public sentiment among Palestinians will quickly shift in favour of Mr. Abbas, said Shibley Telhami, a Middle East scholar at the Washington-based Brookings Institute.
Background
Methodological limitations of prior studies have prevented progress in the treatment of patients with borderline resectable pancreatic adenocarcinoma. Shortcomings have included an absence ...of staging and treatment standards and pre-existing biases with regard to the use of neoadjuvant therapy and the role of vascular resection at pancreatectomy.
Methods
In this manuscript, we review limitations of studies of borderline resectable PDAC reported to date, highlight important controversies related to this disease stage, emphasize the research infrastructure necessary for its future study, and present a recently-approved Intergroup pilot study (Alliance A021101) that will provide a foundation upon which subsequent well-designed clinical trials can be performed.
Results
We identified twenty-three studies published since 2001 which report outcomes of patients with tumors labeled as borderline resectable and who were treated with neoadjuvant therapy prior to planned pancreatectomy. These studies were heterogeneous in terms of the populations studied, the metrics used to characterize therapeutic response, and the indications used to select patients for surgery. Mechanisms used to standardize these and other issues that are incorporated into Alliance A021101 are reviewed.
Conclusions
Rigorous standards of clinical trial design incorporated into trials of other disease stages must be adopted in all future studies of borderline resectable pancreatic cancer. The Intergroup trial should serve as a paradigm for such investigations.
WASHINGTON - The stalled Mideast peace process got a welcome jolt of new life Monday after incoming Palestinian President Mahmoud Abbas offered a hand of friendship to Israel and a new Israeli ...coalition government was approved that is dedicated to withdrawing all Israeli settlements from the Gaza Strip. Abbas received 62 per cent of the votes cast in the election to succeed Yasser Arafat, with whom Israel and the U.S. would not negotiate because they believed he supported terrorism and was "an obstacle to peace. The positive tone in Washington reflects a sharp change in George W. Bush's approach to the Palestinian leadership following Arafat's death in November. The U.S. under the Bush administration had ended direct contact with Arafat, saying he was not a partner for peace. The U.S. had also suspended direct aid payments to the Palestinian Authority.
To evaluate the impact of two different intraperitoneal (IP) chemotherapy regimens on progression-free survival (PFS) among women with newly diagnosed advanced ovarian carcinoma.
Eligible patients ...were randomly assigned to six cycles of IV paclitaxel 80 mg/m
once per week with intravenous (IV) carboplatin area under the curve 6 (IV carboplatin) versus IV paclitaxel 80 mg/m
once per week with IP carboplatin area under the curve 6 (IP carboplatin) versus once every 3 weeks IV paclitaxel 135 mg/m
over 3 hours day 1, IP cisplatin 75 mg/m
day 2, and IP paclitaxel 60 mg/m
day 8 (IP cisplatin). All participants received bevacizumab 15 mg/kg IV every 3 weeks in cycles 2 to 22.
A total of 1,560 participants were enrolled and had 84.8 months of follow-up. The median PFS duration was 24.9 months in the IV carboplatin arm, 27.4 months in the IP carboplatin arm, and 26.2 months in the IP cisplatin arm. For the subgroup of 1,380 patients with stage II/III and residual disease of 1 cm or less, median PFS was 26.9 (IV-carboplatin), 28.7 (IP-carboplatin), and 27.8 months (IP cisplatin), respectively. Median PFS for patients with stage II/III and no residual disease was 35.9, 38.8, and 35.5 months, respectively. Median overall survival for all enrolled was 75.5, 78.9, and 72.9 months, respectively, and median overall survival for stage II/III with no gross residual disease was 98.8 months, 104.8 months, and not reached. Mean patient-reported Functional Assessment of Cancer Therapy neurotoxicity scores (Gynecologic Oncology Group) were similar for all arms, but the mean Trial Outcome Index of the Functional Assessment of Cancer Therapy-Ovary scores during chemotherapy were statistically worse in the IP cisplatin arm.
Compared with the IV carboplatin reference arm, the duration of PFS was not significantly increased with either IP regimen when combined with bevacizumab and was better tolerated than IP cisplatin.
Cell migration has two opposite faces: although necessary for physiological processes such as immune responses, it can also have detrimental effects by enabling metastatic cells to invade new organs. ...In vivo, migration occurs in complex environments and often requires a high cellular deformability, a property limited by the cell nucleus. Here we show that dendritic cells, the sentinels of the immune system, possess a mechanism to pass through micrometric constrictions. This mechanism is based on a rapid Arp2/3-dependent actin nucleation around the nucleus that disrupts the nuclear lamina, the main structure limiting nuclear deformability. The cells' requirement for Arp2/3 to pass through constrictions can be relieved when nuclear stiffness is decreased by suppressing lamin A/C expression. We propose a new role for Arp2/3 in three-dimensional cell migration, allowing fast-moving cells such as leukocytes to rapidly and efficiently migrate through narrow gaps, a process probably important for their function.
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