New Methods for Estimating Labor Supply Functions: A Survey

This paper surveys new methods for estimatifg labor supply functions. A unified framework of analysis is presented. All recent models of labor supply are special cases of a general index function model developed for the analysis o dummy endogenous variables.

Nilpotent Networks and 4D RG Flows

Starting from a general $\mathcal{N} = 2$ SCFT, we study the network of $\mathcal{N} = 1$ SCFTs obtained from relevant deformations by nilpotent mass parameters. We also study the case of flipper field deformations where the mass parameters are promoted to a chiral superfield, with nilpotent vev. Nilpotent elements of semi-simple algebras admit a partial ordering connected by a corresponding directed graph. We find strong evidence that the resulting fixed points are connected by a similar network of 4D RG flows. To illustrate these general concepts, we also present a full list of nilpotent deformations in the case of explicit $\mathcal{N} = 2$ SCFTs, including the case of a single D3-brane probing a $D$- or $E$-type F-theory 7-brane, and 6D $(G,G)$ conformal matter compactified on a $T^2$, as described by a single M5-brane probing a $D$- or $E$-type singularity. We also observe a number of numerical coincidences of independent interest, including a collection of theories with rational values for their conformal anomalies, as well as a surprisingly nearly constant value for the ratio $a_{\mathrm{IR}} / c_{\mathrm{IR}}$ for the entire network of flows associated with a given UV $\mathcal{N} = 2$ SCFT. The $\texttt{arXiv}$ submission also includes the full dataset of theories which can be accessed with a companion $\texttt{Mathematica}$ script.Comment: v2: 73 pages, 12 figures, clarifications and references adde

A damage detection method for instrumented civil structures using prerecorded Green’s functions and cross-correlation

Automated damage detection methods have application to instrumented structures that are susceptible to types of damage that are difficult or costly to detect. The presented method has application to the detection of brittle fracture of welded beam-column connections in steel moment-resisting frames (MRFs), where locations of potential structural damage are known a priori. The method makes use of a prerecorded catalog of Green’s function templates and a cross-correlation method to detect the occurrence, location, and time of structural damage in an instrumented building. Unlike existing methods, the method is designed to recognize and use mechanical waves radiated by the original brittle fracture event, where the event is not known to have occurred with certainty and the resulting damage may not be visible. An experimental study is conducted to provide insight into applying the method to a building. A tap test is performed on a small-scale steel frame to test whether cross-correlation techniques and catalogued Green’s function templates can be used to identify the occurrence and location of an assumed-unknown event. Results support the idea of using a nondestructive force to characterize the building response to high-frequency dynamic failure such as weld fracture

3Dscanner

This project entails designing, prototyping, and testing a 3D scanner. The device that we are building uses LIDAR to take position data of a 3D object, then analyze and encode the sensor data as an STL file that can later be 3D printed out at the same resolution. We aim to build an affordable, high-performance 3D scanner that takes advantage of the falling cost of LIDAR in order to bring 3D scanning capabilities to individuals, the maker community, and even small businesses. We begin this process by choosing a sensor, the YDLIDAR X4, as our primary method of taking position data of the object. We take calibration data with this sensor to ensure that it is suitable to our needs. In doing so, we find that we may need to incorporate certain statistical methods, like dithering, in order to increase the accuracy of the system. We determine an effective layout for scanning all sides of an object, overcoming obstacles like scanning objects with concave surfaces. The physical system is mocked up in Solidworks, enabling us to 3D print, laser cut, and buy all the necessary components of the system. The system is constructed while an interactive user interface is created. We develop an algorithm for turning individual data points from the raw data of the X4 sensor into 3D printable STL files, and interface it with a program that controls the motors to take consistent, comprehensive scans of any object on the platform. In the end, we find two limitations of LIDAR in 3D scanning systems - high-gloss black surfaces and certain steep angles cannot be scanned adequately by LIDAR. However, once our system is constructed, we are able to take 3D scans of common objects, and even 3D print one of our scanned objects. The scan is compared to the original object, and the dimensional accuracy of our scanner is verified

From LATE to MTE : Alternative methods for the evaluation of policy interventions

This paper provides an introduction into the estimation of marginal treatment effects (MTE). Compared to the existing surveys on the subject, our paper is less technical and speaks to the applied economist with a solid basic understanding of econometric techniques who would like to use MTE estimation. Our framework of analysis is a generalized Roy model based on the potential outcomes framework, within which we define different treatment effects of interest, and review the well-known case of IV estimation with a discrete instrument resulting in a local average treatment effect (LATE). Turning to IV estimation with a continuous instrument, we demonstrate that the 2SLS estimator may be viewed as a weighted average of LATEs and discuss MTE estimation as an alternative and more informative way of exploiting a continuous instrument. We clarify the assumptions underlying the MTE framework, its relation to the correlated random coefficients model, and illustrate how the MTE estimation is implemented in practice

A Method to Detect Structural Damage Using High-Frequency Seismograms

A numerical study is performed to gain insight into applying a novel method to detect high-frequency dynamic failure in buildings. The method relies on prerecorded catalog of Green's functions for instrumented buildings. Structural failure during a seismic event is detected by screening continuous data for the presence of waveform similarities to each of the cataloged building responses. In the first part of this numerical study, an impulse-like force is applied to a beam column connection in a linear elastic steel frame. A time-reversed reciprocal method is used to demonstrate that the resulting simulated displacements can be used to determine the absolute time and location of the applied force. In the second part of the study, a steel frame's response to two loading cases, an impulse-like force and an opening crack tensile stress, is computed on a temporal scale of microseconds. Results indicate that the velocity waveform generated by a tensile crack can be approximated by the velocity waveform generated by an impulse-like force load applied at the proper location. These results support the idea of using a nondestructive impulse-like force (e.g. hammer blow) to characterize the building response to high-frequency dynamic failure (e.g. weld fracture)

Formal verification of a microcoded VIPER microprocessor using HOL

The Royal Signals and Radar Establishment (RSRE) and members of the Hardware Verification Group at Cambridge University conducted a joint effort to prove the correspondence between the electronic block model and the top level specification of Viper. Unfortunately, the proof became too complex and unmanageable within the given time and funding constraints, and is thus incomplete as of the date of this report. This report describes an independent attempt to use the HOL (Cambridge Higher Order Logic) mechanical verifier to verify Viper. Deriving from recent results in hardware verification research at UC Davis, the approach has been to redesign the electronic block model to make it microcoded and to structure the proof in a series of decreasingly abstract interpreter levels, the lowest being the electronic block level. The highest level is the RSRE Viper instruction set. Owing to the new approach and some results on the proof of generic interpreters as applied to simple microprocessors, this attempt required an effort approximately an order of magnitude less than the previous one