1,408 research outputs found
Implementation and Investigation of a Compact Circular Wide Slot UWB Antenna with Dual Notched Band Characteristics using Stepped Impedance Resonators
A coplanar waveguide (CPW) fed ultra-wideband (UWB) antenna with dual notched band characteristics is presented in this paper. The circular wide slot and circular radiation patch are utilized to broaden the impedance bandwidth of the UWB antenna. The dual notched band functions are achieved by employing two stepped impedance resonators (SIRs) which etched on the circular radiation patch and CPW excitation line, respectively. The two notched bands can be controlled by adjusting the dimensions of the two stepped impedance resonators which give tunable notched band functions. The proposed dual notched band UWB antenna has been designed in details and optimized by means of HFSS. Experimental and numerical results show that the proposed antenna with compact size of 32 × 24 mm2, has an impedance bandwidth range from 2.8 GHz to 13.5 Hz for voltage standing-wave ratio (VSWR) less than 2, except the notch bands 5.0 GHz - 6.2 GHz for HIPERLAN/2 and IEEE 802.11a (5.1 GHz - 5.9 GHz) and 8.0 GHz - 9.3 GHz for satellite and military applications
Research on Advanced Control Strategies for Vehicle Active Seat Suspension Systems
Vehicle seat suspensions play a very important role in vibration reduction for vehicle drivers, especially for some heavy vehicles. Compared with small vehicles, these heavy vehicle drivers suffer much more from vibrations, which influence driving comfort and may cause health problems, so seat suspensions are necessary for those heavy vehicle drivers to reduce vibrations and improve driving comfort. Advanced control systems and control strategies are investigated for vehicle seat suspensions in this project. Firstly, for an active single-degree of freedom (single-DOF) seat suspension, a singular system-based approach for active vibration control of vehicle seat suspensions is proposed, where the drivers’ acceleration is augmented into the conventional seat suspension model together with seat suspension deflection and relative velocity as system states to make the suspen- sion model as a singular system. Then, an event-triggered H∞ controller is designed for an active seat suspension, where both the continuous and discrete-time event-triggered schemes are considered, respectively. The proposed control method can reduce the work- load of data transmission of the seat suspension system and work as a filter to remove the effect of noise, so it can decrease the precision requirement of the actuator, which can help to reduce the cost of the seat suspension. For complicated seat suspension systems, a singular active seat suspension system with a human body model is also established and an output-feedback event-triggered H∞ controller is designed. The accelerations of each part are considered as part of the system states, which makes the system a singular sys- tem. The seat suspension deflection, relative velocity, the accelerations of the seat frame, body torso, and head are defined as the system outputs. At last, to deal with whole-body vibration, a control system and a robust H∞ control strategy are designed for a 2-DOF seat suspension system. Two H∞ controllers are designed to reduce vertical and rotational vibrations simultaneously. All the proposed seat suspension systems and control methods are verified by simulations and some are also tested by experiments. These simulation and experimental results show their effectiveness and advantages of the proposed methods to improve the driving comfort and some can reduce the workload of data transmission
Muon Anomalous Magnetic Moment and Higgs Potential Stability in the 331 Model from
We consider a model from a
Grand Unified Theory (GUT). In order to explain the anomalous magnetic moments
of muon and electron, we introduce two new scalar triplets without vacuum
expectation values (VEVs) so that the leading contributions to
and can avoid the suppression from small muon mass. In addition,
the Higgs potential stability of this 331 model is studied by giving a set of
sufficient conditions to ensure the boundedness from below of the potential.Comment: 15 page
The resonance, inelastic dark matter, and new physics anomalies in the Simple Extension of the Standard Model (SESM) with general scalar potential
We consider the generic scalar potential with CP-violation, and study the
resonance and inelastic dark matter in the Simple Extension of the Standard
Model (SESM), which can explain the dark matter as well as new physics
anomalies such as the B physics anomalies and muon anomalous magnetic moment,
etc. With the new scalar potential terms, we obtain the mass splittings for the
real and imaginary parts of scalar fields. And thus we can have the DM
co-annihilation process mediated by boson, which couples exclusively to the
CP-even and CP-odd parts of scalar fields. This is a brand new feature compared
to the previous study. For the CP conserving case, we present the viable
parameter space for the Higgs and resonances, which can explain the B
physics anomalies, muon anomalous magnetic moment, and dark matter relic
density, as well as evade the constraint from the XENON1T direct detection
simultaneously. For the CP-violating case, we consider the inelastic dark
matter, and study four concrete scenarios for the inelastic DM-nucleon
scatterings mediated by the Higgs and bosons in details. Also, we present
the benchmark points which satisfy the aforementioned constraints. Furthermore,
we investigate the constraints from the dark matter-electron inelastic
scattering processes mediated by the Higgs and bosons in light of the
XENONnT data. We show that the constraint on the mediated process is weak,
while the Higgs mediated process excludes the dark matter with mass around
several MeV.Comment: 22 pages, 6 figures, 5 table
The quirk trajectory
We for the first time obtain the analytical solution for the quirk equation
of motion in an approximate way. Based on it, we study several features of
quirk trajectory in a more precise way, including quirk oscillation amplitude,
number of periods, as well as the thickness of quirk pair plane. Moreover, we
find an exceptional case where the quirk crosses at least one of the tracking
layers repeatedly. Finally, we consider the effects of ionization energy loss
and fixed direction of infracolor string for a few existing searches.Comment: 22 pages, 8 figure
Naive Bayesian Automatic Classification of Railway Service Complaint Text Based on Eigenvalue Extraction
Railways have developed rapidly in China for several decades. The hardware of railways has already reached the world\u27s leading level, but the level of service of these railways still has room for improvement. The railway management department receives a large number of passenger complaints every year and records them in text, which needs to be classified and analyzed. The text of railway complaints includes characteristics spanning wide business coverage, various events, serious colloquialisms, interference and useless information. When using the direct classification via traditional text categorization, the classification accuracy is low. The key to the automatic classification of such text lies in an eigenvalue extraction. The more accurate the eigenvalue extraction, the higher the accuracy of text classification. In this paper, the TF-IDF algorithm, TextRank algorithm and Word2vec algorithm are selected to extract text eigenvalues, and a railway complaint text classification method is constructed with a naive Bayesian classifier. The three types of eigenvalue extraction algorithms are compared. The TF-IDF algorithm, based on eigenvalue extraction, achieves the highest automatic text classification accuracy
- …