Function by Switching: Heterodiazocines

Exceptional Points of Degeneracy Induced by Linear Time-Periodic Variation

摘要： We present a general theory of exceptional points of degeneracy (EPD) in periodically time-variant systems. We show that even a single resonator with a time-periodic component is able to develop EPDs, contrary to parity-time- (PT) symmetric systems that require two coupled resonators. An EPD is a special point in a system parameter space at which two or more eigenmodes coalesce in both their eigenvalues and eigenvectors into a single degenerate eigenmode. We demonstrate the conditions for EPDs to exist when they are directly induced by time-periodic variation of a system without loss and gain elements. We also show that a single resonator system with zero time-average loss-gain exhibits EPDs with purely real resonance frequencies, yet the resonator energy grows algebraically in time since energy is injected into the system from the time-variation mechanism. Although the introduced concept and formalism are general for any time-periodic system, here, we focus on the occurrence of EPDs in a single LC resonator with time-periodic modulation. These findings have significant importance in various electromagnetic and photonic systems and pave the way for many applications, such as sensors, amplifiers, and modulators. We show a potential application of this time-varying EPD as a highly sensitive sensor.

The LXe calorimeter and the pixelated timing counter in the MEG II experiment

摘要： The MEG experiment is to look for a lepton flavor violating μ + → e+γ decay with an unprecedented sensitivity, and we set an upper limit of the branching ratio for this decay, 5.7 × 10?13 at 90% C.L. in 2013 which is a twenty times more stringent limit than the previous experiment, MEGA. Since the sensitivity improvement was limited by the accidental background, we have considered the major detector upgrade. A proposal was submitted to PSI committee, and was approved in 2013, which aims at a sensitivity enhancement of one order of magnitude compared with the current MEG experiment. Here mainly two components of the MEG detector will be introduced, a γ-ray calorimeter with 900 L of liquid xenon (LXe), and a pixelated timing counter. The LXe detector will be improved by increasing the granularity at the incident face, by replacing the current PMTs with a larger number of smaller photosensors (MPPC) and optimizing the photosensor layout also on the lateral faces. A new highly segmented, fast timing counter array will replace the old system to allow improved timing resolution capabilities.

[IEEE 2018 18th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM) - Waterloo, ON (2018.8.19-2018.8.22)] 2018 18th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM) - Series Expansions for Matrix Inverses

摘要： Various convergent matrix series formulae for the inverse of positive definite matrices are derived starting from series expansions of a simple matrix exponential function. The structure of these series assures a stable numerical computation since successive terms of the series are obtained through a multiplication with a matrix whose condition becomes better and better as the computation progresses.

[IEEE 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Design and Optimization of a Solar Power Conversion System for Space Applications

摘要： This manuscript details a design method for a 500kW solar power based microgrid system for space applications. The design method utilizes multi-objective optimization with the Genetic Algorithm considering four parameters that characterize solar power based microgrids (battery voltage, PV maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular DC-DC micro-converters, of which four topologies (buck, boost, buck-boost and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56W/kg, with optimized result of 743.7V battery voltage, 439.5W PV maximum power, 182.7V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54W/cm3, a specific power of 3.76W/g, and operated for over 267 hours of 11-minute low temperature cycles from 0oC to -140oC.

Dual Parallel Multi-electrode Traveling Wave Mach-Zehnder Modulator for 200 Gb/s Intra-datacenter Optical Interconnects

摘要： We present a silicon photonic dual parallel multi-electrode Mach-Zehnder modulator (MEMZM) based transmitter targeting 200 Gb/s 4-level pulse amplitude modulation (PAM4) short reach transceivers. The MEMZMs have an average Vπ and electro-optic (EO) bandwidth of 5 V and 38 GHz, respectively. The transmitter is characterized versus receiver equalizer taps, received signal power, driving voltage swing, crosstalk voltage swing, bitrate, and reach. Results reveal that using only a 3-tap equalizer at the receiver, 100 Gb/s PAM4 net rate per lane can be achieved at a bit error rate (BER) below the KP4 forward error correction (KP4-FEC) threshold of 2.4 × 10?4. Moreover, up to 128 Gb/s can be received at a BER below the KP4-FEC threshold using only 2 Vpp and 1 Vpp driving the MEMZM segments. Then, both MEMZMs are driven simultaneously to assess the crosstalk impact on the BER performance at parallel operation. Driven by four binary signals, we demonstrate 200 Gb/s PAM4 transmission over up to 10 km of single mode fiber at a BER below the KP4-FEC threshold.

Sizing and improved grid integration of residential PV systems with heat pumps and battery storage systems

摘要： In the future, the remuneration of photovoltaic (PV) grid feed-in might significantly drop in Germany and questions arise if small-scale PV systems remain economically attractive. However, battery storage systems (BSSs) and sector coupling with heat pumps (HPs) provide promising opportunities to increase PV self-consumption and the value of local energy generation, but change the dynamics of PV grid integration. Thus, an optimization model is proposed to enable all involved stakeholders to analyze interdependencies between different flexibility options for PV systems, incentive and grid integration. A case study-based approach allows an efficient evaluation of future PV systems with BSSs and HPs, the impact of such decentralized power-heat-storage systems on grid integration as well as proper incentive setting for sector coupling. The analysis shows that such shifting technologies are required to avoid undersizing of PV systems. BSSs only provide a benefit for the adoption of inflexible HPs, which is not preferable from a grid integration point of view. Operational incentives, such as peak charges and PV feed-in limits, offer a chance to foster PV grid integration and use new flexibilities in a grid-supporting way. The adoption of market-oriented operation leads to small benefit for such systems, which heavily rely on PV self-consumption.

Mixed Logical Dynamical Nonlinear Model Predictive Controller for Large-Scale Solar Fields

摘要： This paper presents a control algorithm for reducing heat losses caused by clouds in large solar fields. The formulation is based on a Mixed Logical Dynamical (MLD) representation of the solar field plus the application of a Practical Nonlinear Model Predictive Controller (PNMPC) for calculating the optimal control action. The main purpose of the controller is to deactivate fields with inlet temperature greater than outlet temperature and to manipulate the oil flow rate of the activated fields for tracking the reference of the outlet temperature. A simplified lumped parameters model is used for prediction and simulation of the solar fields.

Error rate and ergodic capacity of RF-FSO system with partial relay selection in the presence of pointing errors

摘要： This paper presents an analysis of a multiple dual-hop relaying system, which is composed of km-class radio frequency (RF)-free-space optical (FSO) links. Partial relay selection based on outdated channel state information (CSI) is employed in order to select active relay for further transmission. Amplify-and-forward relaying protocol is utilized. The RF links are assumed to be subject to Rayleigh fading, and the FSO links are influenced by both Gamma-Gamma atmospheric turbulence and pointing errors. On the basis of our previously derived expression for cumulative distribution function of the equivalent signal-to-noise ratio of the whole system, we derive novel analytical expressions for the average bit-error rate (BER) and ergodic capacity that are presented in terms of the Meijer’s G-function and extended generalized bivariate Meijer’s G-function, respectively. The numerical results are confirmed by Monte Carlo simulations. Considering the effect of time-correlation between outdated CSI and actual CSI related to the RF channel at the time of transmission, the average BER and the ergodic capacity dependence on various system and channel parameters are observed and discussed. The results illustrate that the temporal correlation between outdated and actual CSI has strong effect on system performance, particularly on BER values, when FSO hop is influenced by favorable conditions.

Development of the readout system for a time projection chamber prototype

摘要： A new GEM-TPC prototype with a laser calibration system is being designed to study the key issues of high-precision track detection whose aimed spatial resolution is better than 100 μm. Meanwhile, a readout system with scalability for the TPC is also being developed. Design of the readout system is based on the architecture of front-end ASICs and commercial ADCs for its advantages at high count rates. Given the requirement of several hundred channels, the system is composed of multiple front-end cards and DAQ boards. The DAQ boards are daisy-chained via bidirectional optical fibers, which transmit clock, trigger, data and control signals simultaneously. To achieve timing synchronization, the GigaBit Transceiver (GBT) firmware is employed to ensure fixed latency between the boards. This paper is focused on the design and setup of the DAQ system, including clock structure, trigger alignment, high-speed data acquisition, etc. The DAQ system consisting of 512 channels has been built, and tests have proved that the entire system works correctly and meets the expected requirements.