Three Essays on Inequality of Opportunity and Intergenerational Mobility

Senior Project submitted to The Division of Social Studies of Bard College

Does exchange rate policy matter for economic growth? Vietnam evidence from a co-integration approach

Both economic growth and exchange rate theories suggest that the exchange rate regime could have consequences for the medium-term growth of a country, directly, through its effects on the adjustment to shocks, and indirectly, through its impact on the important determinants of growth. It is, however, surprising that there was little empirical work investigating the indirect relationship between the exchange rate policy and economics growth in the case of a specific country. In a co-integration framework, our research attempts to fill the gap by econometrically investigating the possible impacts of exchange rate regime on economic growth through two main channels - Foreign direct investment (FDI) and Exports - in the case of Vietnam - a successful example of a transitional economy.Exports, Exchange Rate, FDI, Growth, Co-integration

Shaping spectral leakage for IEEE 802.11 p vehicular communications

IEEE 802.11p is a recently defined standard for the physical (PHY) and medium access control (MAC) layers for Dedicated Short-Range Communications. Four Spectrum Emission Masks (SEMs) are specified in 802.11p that are much more stringent than those for current 802.11 systems. In addition, the guard interval in 802.11p has been lengthened by reducing the bandwidth to support vehicular communication (VC) channels, and this results in a narrowing of the frequency guard. This raises a significant challenge for filtering the spectrum of 802.11p signals to meet the specifications of the SEMs. We investigate state of the art pulse shaping and filtering techniques for 802.11p, before proposing a new method of shaping the 802.11p spectral leakage to meet the most stringent, class D, SEM specification. The proposed method, performed at baseband to relax the strict constraints of the radio frequency (RF) front-end, allows 802.11p systems to be implemented using commercial off-the- shelf (COTS) 802.11a RF hardware, resulting in reduced total system cost

Efficient multi-standard cognitive radios on FPGAs

Cognitive radios that support multiple standards and modify operation depending on environmental conditions are becoming more important as the demand for higher bandwidth and efficient spectrum use increases. Traditional implementations in custom ASICs cannot support such flexibility, with standards changing at a faster pace, while software baseband implementations fail to achieve the performance required. Hence, FPGAs offer an ideal platform bringing together flexibility, performance, and efficiency. This work explores the possible techniques for designing multi-standard radios on FPGAs, and explores how partial reconfiguration can be leveraged in a way that is amenable for domain experts with minimal FPGA knowledge

An Efficient Data-aided Synchronization in L-DACS1 for Aeronautical Communications

L-band Digital Aeronautical Communication System type-1 (L-DACS1) is an emerging standard that aims at enhancing air traffic management (ATM) by transitioning the traditional analog aeronautical communication systems to the superior and highly efficient digital domain. L-DACS1 employs modern and efficient orthogonal frequency division multiplexing (OFDM) modulation technique to achieve more efficient and higher data rate in comparison to the existing aeronautical communication systems. However, the performance of OFDM systems is very sensitive to synchronization errors. L-DACS1 transmission is in the L-band aeronautical channels that suffer from large interference and large Doppler shifts, which makes the synchronization for L-DACS more challenging. This paper proposes a novel computationally efficient synchronization method for L-DACS1 systems that offers robust performance. Through simulation, the proposed method is shown to provide accurate symbol timing offset (STO) estimation as well as fractional carrier frequency offset (CFO) estimation in a range of aeronautical channels. In particular, it can yield excellent synchronization performance in the face of a large carrier frequency offset.Comment: In the proceeding of International Conference on Data Mining, Communications and Information Technology (DMCIT

An Efficient Spectral Leakage Filtering for IEEE 802.11af in TV White Space

Orthogonal frequency division multiplexing (OFDM) has been widely adopted for modern wireless standards and become a key enabling technology for cognitive radios. However, one of its main drawbacks is significant spectral leakage due to the accumulation of multiple sinc-shaped subcarriers. In this paper, we present a novel pulse shaping scheme for efficient spectral leakage suppression in OFDM based physical layer of IEEE 802.11af standard. With conventional pulse shaping filters such as a raised-cosine filter, vestigial symmetry can be used to reduce spectral leakage very effectively. However, these pulse shaping filters require long guard interval, i.e., cyclic prefix in an OFDM system, to avoid inter-symbol interference (ISI), resulting in a loss of spectral efficiency. The proposed pulse shaping method based on asymmetric pulse shaping achieves better spectral leakage suppression and decreases ISI caused by filtering as compared to conventional pulse shaping filters

SOUND TRANSMISSION ACROSS A FINITE SIMPLY SUPPORTED DOUBLE-LAMINATED COMPOSITE PLATE WITH ENCLOSED AIR CAVITY

ABSTRACTSound transmission across a finite orthotropic laminated double-composite plate with enclosed air cavity on an infinite acoustic rigid baffle is investigated analytically. Sound velocity potential method combined with simply supported boundary conditions is used instead of traditional methods, has good scalability and is important for studies of acoustic vibration of structures. The sound transmission loss is calculated from the ratio of incident to transmitted acoustic powers. Specifically, the focus is placed on the effects of several key system parameters on sound transmission including the plate dimensions, the laminate configurations, the boundary conditions, and the composite materials are systematically examined

CIDPro: Custom Instructions for Dynamic Program Diversification

Timing side-channel attacks pose a major threat to embedded systems due to their ease of accessibility. We propose CIDPro, a framework that relies on dynamic program diversification to mitigate timing side-channel leakage. The proposed framework integrates the widely used LLVM compiler infrastructure and the increasingly popular RISC-V FPGA soft-processor. The compiler automatically generates custom instructions in the security critical segments of the program, and the instructions execute on the RISC-V custom co-processor to produce diversified timing characteristics on each execution instance. CIDPro has been implemented on the Zynq7000 XC7Z020 FPGA device to study the performance overhead and security tradeoffs. Experimental results show that our solution can achieve 80% and 86% timing side-channel capacity reduction for two benchmarks with an acceptable performance overhead compared to existing solutions. In addition, the proposed method incurs only a negligible hardware area overhead of 1% slices of the entire RISC-V system

RESEARCH ON ION EXCHANGE CAPACITY OF OXIDIZEDACTIVATED CARBON

Ion exchange capacity of oxidized activated carbon (OAC) by HNO3 and surface treatment by NaOH solution was investigated. The HNO3oxidizedfunctional groups on the activated carbon surface, such as ketone, carboxylic acid and its derivatives, to maximum oxidation state. The OAC surface played the role as cation exchanger for adsorption of inorganic compounds, especially metallic cations. The adsorption capacity of OAC was investigated in batch mode with three representative ions with different valence from +1 to +3 (NH4+, Ca2+, Cr3+). The adsorption process was demonstrated by Langmuir and Freundlich isothermal model, and the maximum adsorption capacity according to Langmuir isothrermal equation was 20.4 mg/g for NH4+, 43.5 mg/g for Ca2+ and 38.5 mg/g for Cr3+. The results showed the OAC modified by HNO3 and surface treatment by NaOH solution improved adsorption capacity of AC for cations in solution to a higher level.

Distributed two-time-scale methods over clustered networks

In this paper, we consider consensus problems over a network of nodes, where the network is divided into a number of clusters. We are interested in the case where the communication topology within each cluster is dense as compared to the sparse communication across the clusters. Moreover, each cluster has one leader which can communicate with other leaders in different clusters. The goal of the nodes is to agree at some common value under the presence of communication delays across the clusters. Our main contribution is to propose a novel distributed two-time-scale consensus algorithm, which pertains to the separation in network topology of clustered networks. In particular, one scale is to model the dynamic of the agents in each cluster, which is much faster (due to the dense communication) than the scale describing the slowly aggregated evolution between the clusters (due to the sparse communication). We prove the convergence of the proposed method in the presence of uniform, but possibly arbitrarily large, communication delays between the leaders. In addition, we provided an explicit formula for the convergence rate of such algorithm, which characterizes the impact of delays and the network topology. Our results shows that after a transient time characterized by the topology of each cluster, the convergence of the two-time-scale consensus method only depends on the connectivity of the leaders. Finally, we validate our theoretical results by a number of numerical simulations on different clustered networks