PRINTABLE SOLID-STATE RECHARGEABLE POWER SOURCES VIA HETERO-COLLOIDAL CHEMISTRY CONTROL

Department of Energy Engineering (Battery Science and Technology)Forthcoming smart energy era, which will find widespread use of flexible/wearable electronic devices, Internet-of-Things (IOTs), electric vehicles (EVs) and grid-scale energy storage systems (ESSs), is in relentless pursuit of high-energy/safe rechargeable power sources. The rechargeable energy storage systems could be suggested as a promising solution to fulfill the stringent requirements for flexible electronics. From the cell manufacturing point of view, conventional rechargeable batteries with fixed shapes and sizes are generally fabricated by winding (or stacking) cell components (such as anodes, cathodes and microporous separator membranes) and then packaging them with (cylindrical-/rectangular-shaped) metallic canisters or pouch films, finally followed by injection of liquid electrolytes. In particular, the use of liquid electrolytes gives rise to serious concerns in cell assembly because they require strict packaging materials to avoid leakage problems and also separator membranes to prevent electrical contact between electrodes. For these reasons, the conventional cell assembly and materials have pushed the batteries to lack of variety in form factors, thus imposing formidable challenges on their integration into versatile-shaped electronic devices. Printing is known to be a simple and reliable technique capable of imparting various surface functionality to a wide diversity of substrates. Recently, besides traditional application fields of printing technology for commodity interests, printed electronics has emerged as an attractive industry due to its process benefits enabling facile fabrication of solution-processable thin-film transistors and integrated circuits. In this dissertation, focused on development of printable solid-state rechargeable power sources (including lithium-ion and lithium-sulfur batteries) with exceptional form factors and aesthetic versatility, which lie far beyond those achievable with conventional battery technologies. In addition, rheo-electrical properties of the printable battery components are systematically elucidated to better understand bi-continuous ion/electron transport phenomena and also printing processability.ope

Two-dimensional heterogeneous photonic bandedge laser

We proposed and realized a two-dimensional (2D) photonic bandedge laser surrounded by the photonic bandgap. The heterogeneous photonic crystal structure consists of two triangular lattices of the same lattice constant with different air hole radii. The photonic crystal laser was realized by room-temperature optical pumping of air-bridge slabs of InGaAsP quantum wells emitting at 1.55 micrometer. The lasing mode was identified from its spectral positions and polarization directions. A low threshold incident pump power of 0.24mW was achieved. The measured characteristics of the photonic crystal lasers closely agree with the results of real space and Fourier space calculations based on the finite-difference time-domain method.Comment: 14 pages, 4 figure

Semiparametric models for joint analysis of longitudinal data and counting processes

In this dissertation, we study statistical methodology for joint modeling that correctly controls for the interplay among longitudinal and counting processes and makes the most efficient use of data. Three types of joint modeling approaches are proposed based on three different purposes of studies. In the first topic, we develop a method for joint modeling of longitudinal data and recurrent events in the presence of an informative terminal event. We focus on data from patients who experience the same type of event at multiple times, such as multiple infection episodes or recurrent strokes, have longitudinal biomarkers, and may be subject to an event, for example death, that makes further observations impossible. To analyze such complicated data, we propose joint models based on a likelihood approach. A broad class of transformation models for the cumulative intensity of recurrent events and the cumulative hazard of the terminal event is considered. We propose to estimate all the parameters using nonparametric maximum likelihood estimators (NPMLE), and we provide computationally efficient EM algorithms to implement the proposed inference procedure. Asymptotic properties of the estimators are shown to be asymptotically normal and semiparametrically efficient. Finally, we evaluate the performance of the proposed method through extensive simulations and application to real data. In the second topic, we develop a method for joint modeling of longitudinal and cure-survival data. By cure-survival data, we mean time-to-event data in which a certain proportion of patients never have any event during a sufficiently long follow-up period. These patients are believed to have been cured by treatment, such as radiation therapy or an initial surgery, and are often the source of heavy tail probabilities in survival curves. To take into account the possibility of patients being cured, we propose to model time-to-event through a transformed promotion time cure model, jointly with a linear mixed effects model for longitudinal data. Due to transformations applied to the promotion time cure model, the proposed method is able to be used in cases where the proportionality assumption does not hold. All the parameters are estimated using NPMLEs, and inference procedures are implemented via a simple EM algorithm. Asymptotic properties of the proposed NPMLEs are derived based on empirical process theory. Simulation studies are conducted and the method is applied to the ARIC data in order to demonstrate the small-sample performance of the proposed method. In the third topic, we develop a partially linear model for longitudinal data with informative censoring, where the main interest is in making inferences about the individual's trajectory of longitudinal responses, which may be informatively censored. Since a fully parameterized mean structure may be insufficient to capture the underlying patterns of longitudinal and event processes, we propose to use a partially linear model for longitudinal responses, where an unspecified underlying function is formulated along with linear covariate effects, and a transformation model is used for informative censoring times. We employ a sieve estimation for the nonparametric trajectory of longitudinal responses, where the unknown trajectory is approximated by cubic B-spline basis functions. All parameters are estimated based on a likelihood approach, and inference procedures are implemented via the EM algorithm. We also investigate a reliable way to select the number of knots and the best transformation. Through empirical process theory, asymptotic properties of the proposed estimators are shown to provide desirable properties. The validity of the proposed method is confirmed by simulated and real data examples

UV-cured Solid-State Composite Polymer Electrolytes for Flexible/Safer Lithium-Ion Batteries

Department of Energy Engineering (Battery Science and Technology)Lithium-ion batteries (LIBs), as a compelling portable power source, have dominated the portable device market due to their high energy density, high voltage window and long cyclability. Flexible LIBs have received great attention as a key component to enable future flexible electronic devices as roll-up displays, touch screens, conformable active radio-frequency identification tags, wearable sensors and implantable medical devices. A number of designs for flexible LIBs have been reported in recent years. In this study, a new class of UV (ultraviolet)-cured mechanically-compliant, dendrite growth-suppressing and thermally-stable composite polymer electrolytes (CPEs) are developed for use in flexible LIBs. These new CPEs are fabricated through an elaborate combination of UV-cured ethoxylated trimethylolpropane triacrylate macromer (serving as a mechanical framework) and Al2O3 nanoparticles (as a functional filler) under the presence of liquid electrolyte (1M LiPF6 in ethylene carbonate/propylene carbonate = 1/1 v/v or succinonitrile-mediated plastic crystal electrolyte (PCE)). A salient structural feature of the CPE is the close-packed Al2O3 nanoparticles in the liquid electrolyte-swollen ETPTA macromer matrix. Owing to this unique morphology, the CPE provides significant improvements in the mechanical bendability and suppression of lithium dendrite growth during repeated charge/discharge cycling of cells. In addition, the CPE precursor mixture (i.e., prior to UV irradiation) with well-tailored rheological properties, via collaboration with UV-assisted imprint lithography technique, enables the generation of micropatterned CPE with tunable dimensions. Notably, the cell incorporating the self-standing PCE based CPE, which acts as thermally-stable electrolyte and also separator membrane, maintains stable charge/discharge behavior even after exposure to thermal shock condition (= 130 ℃/0.5 h), while a control cell assembled with carbonate-based liquid electrolyte and polyethylene separator membrane loses electrochemical activity. We envision that the material/structural concept used for the CPEs is simple and versatile, which thus holds a great deal of promise as a platform electrolyte strategy for next-generation flexible LIBs.ope

Factors Affecting the Work-life Balance of Flight Instructors

In recent years, work-life balance has become a key area of concern for employees and organizations all over the world. Employees’ work-life balance has a direct impact on their quality of life, work, and personal well-being. While many researchers have conducted studies investigating the factors affecting work-life balance for various group of employees—e.g., remote workers, female bank employees, corporate managers, physicians and clinicians, etc., work-life balance for flight instructors has never been studied. Flight instructors provide critical service for the aviation industry by teaching students how to fly aircrafts through classroom, simulator, and live flight instruction. They are required to have a pilot\u27s license and instructor certification. Although flight instructors usually do not fly more than eight hours a day, their work schedules can be irregular and unpredictable. They may also be required to work during weekends and evening hours. Naturally, balancing work and family responsibilities is not easy for flight instructors. This research will investigate the factors affecting work-life balance for flight instructors. Data will be collected using an online questionnaire and respondents will be selected through convenience sampling. Data analysis will be carried out by using confirmatory factor analysis. This work-in-progress poster contributes to the aviation industry by providing valuable insight into how flight instructors perceive the quality of their work-life balance. Results of this paper should benefit readers better understand many critical aspects of flight instructors’ duties and responsibilities. Results should also help increasing flight instructors’ productivity, well-being, and engagement, and reducing their stress and absenteeism

A photonic-crystal optical antenna for extremely large local-field enhancement

We propose a novel design of an all-dielectric optical antenna based on photonic-band-gap confinement. Specifically, we have engineered the photonic-crystal dipole mode to have broad spectral response (Q ~70) and well-directed vertical-radiation by introducing a plane mirror below the cavity. Considerably large local electric-field intensity enhancement ~4,500 is expected from the proposed design for a normally incident planewave. Furthermore, an analytic model developed based on coupled-mode theory predicts that the electric-field intensity enhancement can easily be over 100,000 by employing reasonably high-Q (~10,000) resonators

Dose Finding for Continuous and Ordinal Outcomes with a Monotone Objective Function: A Unified Approach

In many phase I trials, the design goal is to find the dose associated with a certain target toxicity rate. In some trials, the goal can be to find the dose with a certain weighted sum of rates of various toxicity grades. For others, the goal is to find the dose with a certain mean value of a continuous response. In this article, we describe a dose-finding design that can be used in any of the dose-finding trials described above, trials where the target dose is defined as the dose at which a certain monotone function of the dose is a prespecified value. At each step of the proposed design, the normalized difference between the current dose and the target is computed. If that difference is close to zero, the dose is repeated. Otherwise, the dose is increased or decreased, depending on the sign of the difference

PG-RCNN: Semantic Surface Point Generation for 3D Object Detection

One of the main challenges in LiDAR-based 3D object detection is that the sensors often fail to capture the complete spatial information about the objects due to long distance and occlusion. Two-stage detectors with point cloud completion approaches tackle this problem by adding more points to the regions of interest (RoIs) with a pre-trained network. However, these methods generate dense point clouds of objects for all region proposals, assuming that objects always exist in the RoIs. This leads to the indiscriminate point generation for incorrect proposals as well. Motivated by this, we propose Point Generation R-CNN (PG-RCNN), a novel end-to-end detector that generates semantic surface points of foreground objects for accurate detection. Our method uses a jointly trained RoI point generation module to process the contextual information of RoIs and estimate the complete shape and displacement of foreground objects. For every generated point, PG-RCNN assigns a semantic feature that indicates the estimated foreground probability. Extensive experiments show that the point clouds generated by our method provide geometrically and semantically rich information for refining false positive and misaligned proposals. PG-RCNN achieves competitive performance on the KITTI benchmark, with significantly fewer parameters than state-of-the-art models. The code is available at https://github.com/quotation2520/PG-RCNN.Comment: Accepted by ICCV 202

Effect of 5-alpha Reductase Inhibitor on Storage Symptoms in Patients with Benign Prostatic Hyperplasia

Purpose Many patients with benign prostatic hyperplasia (BPH) have storage symptoms. The aim of this study was to evaluate the effects of treatment with a 5-alpha reductase inhibitor (5ARI) on storage symptoms in patients with BPH. Methods This study was conducted in 738 patients with lower urinary tract symptoms secondary to BPH. Patients with a prostate volume of higher than 30 mL on the transrectal ultrasound were classified into two groups: group A, in which an alpha blocker was solely administered for at least 12 months, and group B, in which a combination treatment regimen of an alpha blocker plus 5ARI was used. This was followed by an analysis of the changes in parameters such as the total International Prostate Symptom Score (IPSS), voiding symptom subscore, and storage symptom subscore between the two groups. In addition, we examined whether there was a significant difference between the two groups in the degree of change in storage symptoms between before and after the pharmacological treatment. Results Of the 738 men, 331 had a prostate volume ≥30 mL, including 150 patients in group A and 181 patients in group B. Total IPSS, the voiding symptom subscore, and the storage symptom subscore were significantly lower after treatment than before treatment in both groups (P<0.05). A comparison of the degree of change between before and after treatment, however, showed no significant differences in the storage symptom subscore between the two groups (P>0.05). Conclusions Alpha blocker and 5ARI combination treatment is effective for patients with BPH including storage symptoms. However, 5ARI does not exert a significant effect on storage symptoms in BPH patients

A Comparison of Dimensional Standard of Several Nickel-Titanium Rotary Files

Objectives The aim of this study was to compare the dimensional standard of several nickel-titanium (Ni-Ti) rotary files and verify the size conformity. Materials and Methods ProFile (Dentsply Maillefer), RaCe (FKG Dentaire), and TF file (SybronEndo) #25 with a 0.04 and 0.06 taper were investigated, with 10 in each group for a total of 60 files. Digital images of Ni-Ti files were captured under light microscope (SZX16, Olympus) at 32×. Taper and diameter at D1 to D16 of each files were calculated digitally with AnalySIS TS Materials (OLYMPUS Soft Imaging Solutions). Differences in taper, the diameter of each level (D1 to D16) at 1 mm interval from (ANSI/ADA) specification No. 101 were statistically analyzed using one-way ANOVA and Scheffe\u27s post-hoc test at 95% confidence level. Results TF was the only group not conform to the nominal taper in both tapers (p \u3c 0.05). All groups except 0.06 taper ProFile showed significant difference from the nominal diameter (p \u3c 0.05). Conclusions Actual size of Ni-Ti file, especially TF, was different from the manufacturer\u27s statements