Thermal-porosity characterization data of additively manufactured Ti-6Al-4V thin-walled structure via laser engineered net shaping.

In-process thermal melt pool images and post-fabrication porosity labels are acquired for Ti-6Al-4V thin-walled structure fabricated with OPTOMEC Laser Engineered Net Shaping (LENS™) 750 system. The data is collected for nondestructive thermal characterization of direct laser deposition (DLD) build. More specifically, a Stratonics dual-wavelength pyrometer captures a top-down view of the melt pool of the deposition heat-affected zone (HAZ), which is above 1000∘C, and Nikon X-Ray Computed Tomography (XCT) XT H225 captures internal porosity reflective of lack of fusion during the fabrication process. The pyrometer images provided in Comma Separated Values (CSV) format are cropped to center the melt pool to temperatures above 1000℃, indicative of the shape and distribution of temperature values. Melt pool coordinates are determined using pyrometer specifications and thin wall build parameters. XCT porosity labels of sizes between 0.05 mm to 1.00 mm are registered within 0.5 mm of the melt pool image coordinate. An XCT porosity-labeled table provided in the Excel spreadsheet format contains time stamps, melt pool coordinates, melt pool eccentricity, peak temperature, peak temperature coordinates, pore size, and pore label. Thermal-porosity data utilization aids in generating data-driven quality control models for manufacturing parts anomaly detection.

Alkali treatment facilitates functional nano-hydroxyapatite coating of 3D printed polylactic acid scaffolds.

Autografting is currently the gold standard for treatment of bone defects, but has shown disadvantages in the limited volume of and donor site morbidity associated with harvested bone. Customized bone scaffolds that mimic the mechanical and biological properties of native bone are needed to augment the currently limited bone regeneration strategies. To achieve this goal, a repeated cross-hatch structure with uniform cubic pores was designed and 3D printed using polylactic acid (PLA) via fused deposition modeling (FDM). PLA surfaces were modified by wet chemical (alkali) treatment for either 1 h (1hAT) or 6 h (6hAT), followed by coating with nano-hydroxyapatite (nHA). Our hypotheses were that: (i) 6-hour (but not 1-hour) alkali treatment would enhance nHA coating, (ii) the nHA coating on the 6-hour alkali-treated surface would increase hydrophilicity and cell attachment/proliferation, and (iii) stiffness, but not effective Young's modulus, would be reduced by 6-hour alkali treatment. The effects of AT and nHA coating on scaffold morphology was observed by scanning electron microscopy and quantified using a custom MATLAB script. Chemical composition and hydrophilicity were evaluated via energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy, and water contact angle analyses, respectively. Mechanical testing and in vitro cell culture were further employed to analyze compressive properties, and cell attachment and proliferation, respectively. As expected, 6hAT led to reduced strut width and stiffness, while improving the nHA coating and hydrophilicity. Interestingly, PLA/6hAT but not PLA/6hAT/nHA demonstrated a reduction in effective modulus compared to PLA and PLA/nHA scaffolds. From in vitro experiments, the combined PLA/6hAT/nHA modification resulted in the greatest extent of cell attachment but not proliferation. These results collectively demonstrate that the PLA/6hAT/nHA scaffold exhibits properties that may prove beneficial for cancellous bone regeneration.

Implementing Virtual Reality technology for safety training in the precast/ prestressed concrete industry.

Thousands of people work in the precast/pre-stressed concrete industry every day. Due to the design of the precast/prestressed concrete product itself and the processes required for its production, employees are occasionally exposed to hazards. The industry recognizes this and devotes a significant amount of time and investment to mitigate these hazards and protect employees from harm. It is essential for employees to go through appropriate safety training before starting work in the plant. Practical safety training should be cost-effective, and performance guaranteed, and traditional training procedures include paper-based safety guidelines, lectures, videos, and on-site training. Virtual Reality (VR) provides an innovative approach for safety training as it could offer situational training with negligible risk and at a low cost. In this paper, a VR training module is developed to deliver safety training in a cost-effective yet repeatable manner, aiming to reduce common plant injuries. The module is developed using Unity3D and Visual Studio joint platforms and can be interfaced with using the Oculus Rift/Oculus S. The module addresses three major safety concerns in the plant: personal protective equipment (PPE), the tensioning of strand (the stressing process), and suspended loads. Efficacy and effectiveness analyses were conducted to evaluate the performance of the proposed VR module. The efficacy analysis was based on simulation sickness, user experience, and system usability. This analysis showed that the developed VR module is a user-friendly simulator with minimal simulation sickness. More than 50% of the participants reported no indications of simulation sickness. In addition, an effectiveness analysis was performed based upon a comparative study of this VR training method and the traditional video-based training method. This analysis indicated that VR training is more engaged and provides a better understanding of safety protocols and real-life experience of the precast/prestressed concrete plant.

The impact of varying patient populations on the in-control performance of the risk-adjusted CUSUM chart.

OBJECTIVE: This research is designed to examine the impact of varying patient population distributions on the in-control performance of the risk-adjusted Bernoulli CUSUM chart. DESIGN: The in-control performance of the chart is compared based on sampling the Parsonnet scores with replacement from five realistic subsets of a given distribution. SETTINGS: Five patient mixes with different Parsonnet score distributions are created from a real patient population. MAIN OUTCOME MEASURES: The outcome measures for this research are the in-control average run lengths (ARLs) given varying patient populations. RESULTS: Our simulation results show that the in-control ARLs of the risk-adjusted Bernoulli CUSUM chart with fixed control limits and a given risk-adjustment equation vary significantly for different patient population distributions, and the in-control ARLs decrease as the mean of the Parsonnet scores increases. CONCLUSIONS: The simulation results imply that the control limits should vary based on the particular patient population of interest in order to control the in-control performance of the risk-adjusted Bernoulli CUSUM method.