Development of Process Monitoring Monitoring Strategies for Contamination Control Utilizing a Surface Charge Analyzer

The study done was to develop strategies that utilize the measurement and analytical capabilities of a Semitest Surface Charge Analyzer (SCA 2000) and monitor contamination caused during certain processes and in furnaces in an IC fab. A significant drop in average minority carrier lifetime and an increase in fixed oxide charge was observed. Counterdoping was also observed in one of the furnaces

Novel Transistor Resistance Variation-based Physical Unclonable Functions with On-Chip Voltage-to-Digital Converter Designed for Use in Cryptographic and Authentication Applications

Security mechanisms such as encryption, authentication, and feature activation depend on the integrity of embedded secret keys. Currently, this keying material is stored as digital bitstrings in non-volatile memory on FPGAs and ASICs. However, secrets stored this way are not secure against a determined adversary, who can use specialized probing attacks to uncover the secret. Furthermore, storing these pre-determined bitstrings suffers from the disadvantage of not being able to generate the key only when needed. Physical Unclonable Functions (PUFs) have emerged as a superior alternative to this. A PUF is an embedded Integrated Circuit (IC) structure that is designed to leverage random variations in physical parameters of on-chip components as the source of entropy for generating random and unique bitstrings. PUFs also incorporate an on-chip infrastructure for measuring and digitizing these variations in order to produce bitstrings. Additionally, PUFs are designed to reproduce a bitstring on-demand and therefore eliminate the need for on-chip storage. In this work, two novel PUFs are presented that leverage the random variations observed in the resistance of transistors. A thorough analysis of the randomness, uniqueness and stability characteristics of the bitstrings generated by these PUFs is presented. All results shown are based on an exhaustive testing of a set of 63 chips designed with numerous copies of the PUFs on each chip and fabricated in a 90nm nine-metal layer technology. An on-chip voltage-to-digital conversion technique is also presented and tested on the set of 63 chips. Statistical results of the bitstrings generated by the on-chip digitization technique are compared with that of the voltage-derived bitstrings to evaluate the efficacy of the digitization technique. One of the most important quality metrics of the PUF and the on-chip voltage-to-digital converter, the stability, is evaluated through a lengthy temperature-voltage testing over the range of -40C to +85C and voltage variations of +/- 10% of the nominal supply voltage. The stability of both the bitstrings and the underlying physical parameters is evaluated for the PUFs using the data collected from the hardware experiments and supported with software simulations conducted on the devices. Several novel techniques are proposed and successfully tested that address known issues related to instability of PUFs to changing temperature and voltage conditions, thus rendering our PUFs more resilient to these changing conditions faced in practical use. Lastly, an analysis of the stability to changing temperature and voltage variations of a third PUF that leverages random variations in the resistance of the metal wires in the power and ground grids of a chip is also presented

Assuring reliability in qualitative studies: a health informatics persective

Assuring the validity and reliability of data is an essential component of data collection. While quantitative studies use certain statistical techniques such as ‘Cronbach Alpha’ values for a reliability index, in qualitative studies these type of measures are not widely available, and appear to be predominantly subjective. So, many studies, if at all probe this aspect, highlight what is normally termed as ‘saturation’ and use this as a measure of reliability. While this serves the purpose to some extent, whether researchers can use this as a concrete evidence is questionable. We propose a new approach to assure reliability in qualitative studies, and provide a case study to demonstrate our approach and its benefits. We hope that this serves as a model to many PhD students and other Early Career Researchers who pursue their studies using qualitative approaches

Engineering Method of Prediction of Plume Path of Air Launched Missile

Separation dynamics study of an air-launched missile is a paramount task for ensuring the safety of launch aircraft. The study should certify that there is absolute absence of any physical interference of missile with the aircraft at any circumstance. It is also important to ensure that the interference of rocket motor plume of hot-launched missile does not have any significant effect on the structure, on board electronic components and sensitive parts of the aircraft. The plume ingestion into the aircraft intake is a critical problem which endangers the safety of the aircraft. Therefore, the prediction of plume path of hot-launched missile is a significant part of separation dynamics study. An engineering approach based on a particle tracking method was followed in predicting the plume path in the present work. Further, the method is modified using reverse particle tracking method to make it more efficient. The method is applied in predicting plume path for an air-to air-missile and is found that this approach gives reasonably accurate plume path with minimum computational requirements

A Robust Approach to Find the Control Points for Wide Variety of 3rd Order Bzier Curves

This paper represents a new approach that can recover the control points for wide variety of 3rd order BE9;zier curves. In this regards, the two stage approximation learning algorithm is adopted with some modifications. At 1st stage our key feature is segmentation of the curve which can determine intermediate points of the wide variety of curves. In this respect, an efficient recursive algorithm is used to find out the height of the curve (h) with less iteration. The proposed approach introduced horizontal segmentation rather than vertical segmentation. Different height (H), where the 2nd and 3rd control point are assumed, and also the step-size (2202;), at which the control points are moved toward the actual direction, are used to find out the exact location of the control points. Experimental results demonstrate that our proposing method can recover control points for wide variety of curves with minimum error level and less iteration. Wide variety of curve shapes are used to test the proposing approach and results are presented to prove its effectivenes

Separation Dynamics of Air-to-Air Missile and Validation with Flight Data

Prediction of flight characteristics of a store in the vicinity of an aircraft is vitally important for ensuring the safety of the aircraft and effectiveness of the store to meet the mission objective. Separation dynamics of an agile air-to-air-Missile from a fighter aircraft is numerically simulated using an integrated store separation dynamics suite. Chimera cloud of points along with a grid-free Euler solver is used to obtain aerodynamic force on the missile and the force is integrated using a rigid body dynamics code to obtain the missile position. In the present work, the suite is applied to a flight test case and sensitivity of trajectory variables on launch parameters is studied. Further, the results of the suite are compared with the flight data. The predicted body rates and Euler angles of missile compare well with the flight data. 

Heat-induced SIRT1-mediated H4K16ac deacetylation impairs resection and SMARCAD1 recruitment to double strand breaks

Hyperthermia inhibits DNA double-strand break (DSB) repair that utilizes homologous recombination (HR) pathway by a poorly defined mechanism(s); however, the mechanisms for this inhibition remain unclear. Here we report that hyperthermia decreases H4K16 acetylation (H4K16ac), an epigenetic modification essential for genome stability and transcription. Heat-induced reduction in H4K16ac was detected in humans

Enhancing the ultrafast third order nonlinear optical response by charge transfer in VSe2-reduced graphene oxide hybrid

Nonlinear optical phenomena play a critical role in understanding microscopic light-matter interactions and have far-reaching applications across various fields, such as biosensing, quantum information, optical switching, and all-optical data processing. Most of these applications require materials with high third-order absorptive and refractive optical nonlinearities. However, most materials show weak nonlinear optical responses due to their perturbative nature and often need to be improved for practical applications. Here, we demonstrate that the charge donor-acceptor hybrid of VSe2-reduced graphene oxide (rGO) hybrid exhibits enhanced ultrafast third-order absorptive and refractive nonlinearities compared to the pristine systems, at least by one order of magnitude. Through density functional theory and Bader charge analysis, we elucidate the strong electronic coupling in the VSe2-rGO hybrid, involving the transfer of electrons from VSe2 to rGO. Steady-state and time-resolved photoluminescence (PL) measurements confirm the electronic coupling and charge transfer. Furthermore, we fabricate an ultrafast optical limiter device with better performance parameters, such as an onset threshold of 2.5 mJ cm-2 and differential transmittance of 0.42