The increasing proliferation of distributed energy resources (DERs) on the smart grid has made distributed solar and wind two key contributors to the expanding attack surface of the network; however, there is a lack of proper understanding and enforcement of DER communications security requirements. With vendors employing proprietary methods to mitigate hosts of attacks, the literature currently lacks a clear organization of the protocol-level vulnerabilities, attacks, and solutions mapped to each layer of the logical model such as the OSI stack. To bridge this gap and pave the way for future research by the authors in determining key DER security requirements, this paper conducts a comprehensive review of the key vulnerabilities, attacks, and potential solutions for solar and wind DERs at the protocol level. In doing so, this paper serves as a starting point for utilities, vendors, aggregators, and other industry stakeholders to develop a clear understanding of the DER security challenges and solutions, which are key precursors to comprehending security requirements.

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This study explores the use of mini-fabrication exercises for helping students learn design for rapid prototyping in computer-aided design and prototyping courses in engineering curricula. To this end, we conducted mini-fabrication exercises in ME444 — an undergraduate course at Purdue University. The exercises provide hands-on exposure to design for rapid prototyping principles using simplified design problems. We developed two mini-fabrication exercises in ME444; (i) gear pair design & box design using laser cutting, and (ii) toy catapult design using stereolithography printing. These exercises were tested in a classroom-setting with 51 undergraduate students. Results show the mini-fabrication exercises facilitated students’ learning of geometric dimensioning & tolerancing, part sizing, and material properties in laser cutting and stereolithography printing.

Aims and Objectives: The present study was undertaken for evaluating various hand instrumentation techniques with different instruments in the formation of smear layer. Materials and Methods: One hundred and seventy-five extracted mandibular molars were collected and were cut at cementoenamel junction. Afterward, the distal roots were separated. Working length was determined, and roots were divided into five equal groups with 35 roots in each group as follows: Group A: K-type files with conventional step-back technique, Group B: Canal Master U instrument with clockwise–counterclockwise rotation, Group C: Flex-R ® files with clockwise–counterclockwise rotation, Group D: FlexoFiles ® with conventional step-back technique, and Group E: Nickel titanium files with conventional step-back technique. Biomechanical preparation was done according to their respective groups. The teeth in various groups were scanned under scanning electron microscope and scoring was done. All the results were analyzed by SPSS software version 17.0. Results: Scanning electron microscopic results indicated that apparently there seems to be a significant difference in the scoring of the smear layer between each group at all the three levels, but the difference was statistically nonsignificant. Microleakage was present in all the samples. Nonsignificant results were obtained while comparing the microleakage in between different the groups. However, microleakage was highest in Group D. Conclusion: The amount of smear layer is maximum at the apical third and lesser in the middle third followed by the coronal third in all the groups. All the samples showed microleakage to a varying extent.

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