A Novel Three-Point Modulation Technique for Fractional-N Frequency Synthesizer Applications

This paper presents a novel three-point modulation technique for fractional-N frequency synthesizer applications. Convention modulated fractional-N frequency synthesizers suffer from quantization noise, which degrades not only the phase noise performance but also the modulation quality. To solve this problem, this work proposes a three-point modulation technique, which not only cancels the quantization noise, but also markedly boosts the channel switching speed. Measurements reveal that the implemented 2.4 GHz fractional-N frequency synthesizer using three-point modulation can achieve a 2.5 Mbps GFSK data rate with an FSK error rate of only 1.4 %. The phase noise is approximately -98 dBc/Hz at a frequency offset of 100 kHz. The channel switching time is only 1.1 μs with a frequency step of 80 MHz. Comparing with conventional two-point modulation, the proposed three-point modulation greatly improves the FSK error rate, phase noise and channel switching time by about 10 %, 30 dB and 126 μs, respectively

Nonresponse Bias and Survey Outcome Representativeness: Assessing Reasons for Nonresponse in Follow-up Surveys.

The current study focused on four reasons of passive nonresponse due to noncontact, on-leave, high workload, and technical constrains. Different types of nonrespondents were compared to active nonrespondents and respondents to assess the potential different impacts of nonresponse bias reflected accordingly. Relevant literature was reviewed and hypotheses regarding the mean response comparison of core survey items and organizational attitudes were tested. Data collected from 1,333 military personnel in an initial survey and 605 personnel in its follow-up survey suggested that different types of passive nonrespondents may introduce various degree of nonresponse bias and thus pasive nonresponse should be viewed as a multi-dimensional variable. Contributions, implications, and limitations of the results are discussed

Train Track Misalignment Detection System

A feasible, portable and low-cost detection technique for train track misalignment was proposed. Currently, the detection of orientation movement of train along a flat head rail focuses on using different combination of optical sensor, accelerometer and gyro sensors, separated at several compartment and parts of the train. However, due to high implementation cost and complexity, these systems could not be widely implemented in all of the passenger-loaded compartments train and not suitable to switch from one platform to another, as it requires complex mounted installations. Hence, a MEMS-based Inertia Measurement Unit (IMU) was proposed to be implemented as an alternative low-cost and portable detection solution. The primary objective focuses on identifying potential misaligned track section through tri-axis Euler angles and tri-axis acceleration of the train. Equipped with an onboard Arduino ATMega328 microcontroller, the IMU was programmed through Arduino IDE by using USB-to-UART converter. Direction-cosine-matrix (DCM) algorithm was also implemented to detect and correct numerical error for the gyroscope via reference data from accelerometer. Practical implementation had also being conducted on both car and passenger-loaded train. These data were extracted onto PC for storage and post-processing via MATLAB. The measurements were analyzed and presented with discussion on track characteristics, train motion and noise. Also, analysis through the frequency spectrum over time provides insight onto possible misalignment region. The overall measurement analysis showed good correlation between actual track features and IMU sensor data

LHC τ\tau-rich Tests of Lepton-specific 2HDM for (g−2)μ(g-2)_\mu

The lepton-sepcific (or type X) 2HDM (L2HDM) is an attractive new physics candidate explaining the muon $g-2$ anomaly requiring a light CP-odd boson $A$ and large $\tan\beta$. This scenario leads to $\tau$-rich signatures, such as $3\tau$, $4\tau$ and $4\tau+W/Z$, which can be readily accessible at the LHC. We first study the whole L2HDM parameter space to identify allowed regions of extra Higgs boson masses as well as two couplings $\lambda_{hAA}$ and $\xi_h^l$ which determine the 125 GeV Higgs boson decays $h\to \tau^+\tau^-$ and $h\to AA/AA^*(\tau^+\tau^-)$, respectively. This motivates us to set up two regions of interest: (A) $m_A \ll m_{H} \sim m_{H^\pm}$, and (B) m_A \sim m_{H^\pm} \sim {\cal O}(100) \mbox{GeV} \ll m_H, for which derive the current constraints by adopting the chargino-neutralino search at the LHC8, and then analyze the LHC14 prospects by implementing $\tau$-tagging algorithm. A correlated study of the upcoming precision determination of the 125 GeV Higgs boson decay properties as well as the observation of multi-tau events at the next runs of LHC will be able to shed light on the L2HDM option for the muon $g-2$.Comment: 21 pages, 9 figure

Gating of memory encoding of time-delayed cross-frequency MEG networks revealed by graph filtration based on persistent homology

To explain gating of memory encoding, magnetoencephalography (MEG) was analyzed over multi-regional network of negative correlations between alpha band power during cue (cue-alpha) and gamma band power during item presentation (item-gamma) in Remember (R) and No-remember (NR) condition. Persistent homology with graph filtration on alpha-gamma correlation disclosed topological invariants to explain memory gating. Instruction compliance (R-hits minus NR-hits) was significantly related to negative coupling between the left superior occipital (cue-alpha) and the left dorsolateral superior frontal gyri (item-gamma) on permutation test, where the coupling was stronger in R than NR. In good memory performers (R-hits minus false alarm), the coupling was stronger in R than NR between the right posterior cingulate (cue-alpha) and the left fusiform gyri (item-gamma). Gating of memory encoding was dictated by inter-regional negative alpha-gamma coupling. Our graph filtration over MEG network revealed these inter-regional time-delayed cross-frequency connectivity serve gating of memory encoding