Trends in office internal gains and the impact on space heating and cooling demands

Internal gains from occupants, equipment and lighting contribute a significant proportion of the heat gains in an office space. Looking at trends in Generation-Y, it appears there are two diverging paths for future ICT demand: one where energy demand is carefully regulated and the other where productivity enhancers such as multiple monitors and media walls causes an explosion of energy demand within the space. These internal gains scenarios were simulated on a variety of different building archetypes to test their influence on the space heating and cooling demand. It was demonstrated that in offices with a high quality facade, internal gains are the dominant factor. As a case study, it was shown that natural ventilation is only possible when the ICT demand is carefully regulated

Modelling and analysis of time series of high resolution stellar spectra with differential methods.

PhD ThesisHigh resolution spectroscopic and photometric surveys of M dwarfs in the solar neighbourhood have detected exoplanets with masses and sizes similar to that of the Earth orbiting in the habitable zone of their parent star. These exoplanets are currently the best candidates for follow up observations for the search for life outside our Solar System. However, high resolution spectra ofMdwarfs have blended spectral lines which cause problems for a number of detection and characterisation methods which require the position and identi cation of each line in the spectrum of the star. Scattered starlight from an exoplanet, commonly called re ected light, can be used to characterise the planet including the determination of its albedo and inclination of orbit. The relatively low ux ratio between directly observed starlight and starlight scattered o hot Jupiters make these systems prime candidates for detection of re ected light using high-resolution spectroscopy. The rst detections have been claimed for 51 Peg b but with spectral lines broader than expected. We present an algorithm called di erential least squares deconvolution (dLSD) to be used in exoplanet characterisation which resolves the problems caused by line blending of spectral lines. We then show how dLSD can be used to measure starplanet obliquity measurements of HD189733 and to characterise short term activity in the M dwarf Ross 154. We next determine the expected Doppler shift and broadening of starlight scattered o a planet and provide software called RE ected STARlighT (RESTART) which given an input stellar spectrum will produce the Doppler shifted and broadened spectrum of the re ected starlight. We use RESTART to demonstrate the broadening in 51 Peg b and predict broadening for other hot Jupiter systems. dLSD and RESTART will be used in analysis of data in future high resolution spectroscopic surveys of M dwarfs and hot Jupiters

Instrumentation and algorithms for electrostatic inverse problems

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2001.Includes bibliographical references (leaf 89).This thesis describes tracking objects with low-level electric fields. A physical model is presented that describes the important interactions and the required mathematical inversions. Sophisticated hardware used to perform the measurements is described in detail. Finally, a discussion of the myriad applications for electric field sensing is described. The main application goal for this thesis is to make an efficient 3D mouse using electric field sensing technology.by John Paul Strachan.S.B.M.Eng

Analog Feedback-Controlled Memristor programming Circuit for analog Content Addressable Memory

Recent breakthroughs in associative memories suggest that silicon memories are coming closer to human memories, especially for memristive Content Addressable Memories (CAMs) which are capable to read and write in analog values. However, the Program-Verify algorithm, the state-of-the-art memristor programming algorithm, requires frequent switching between verifying and programming memristor conductance, which brings many defects such as high dynamic power and long programming time. Here, we propose an analog feedback-controlled memristor programming circuit that makes use of a novel look-up table-based (LUT-based) programming algorithm. With the proposed algorithm, the programming and the verification of a memristor can be performed in a single-direction sequential process. Besides, we also integrated a single proposed programming circuit with eight analog CAM (aCAM) cells to build an aCAM array. We present SPICE simulations on TSMC 28nm process. The theoretical analysis shows that 1. A memristor conductance within an aCAM cell can be converted to an output boundary voltage in aCAM searching operations and 2. An output boundary voltage in aCAM searching operations can be converted to a programming data line voltage in aCAM programming operations. The simulation results of the proposed programming circuit prove the theoretical analysis and thus verify the feasibility to program memristors without frequently switching between verifying and programming the conductance. Besides, the simulation results of the proposed aCAM array show that the proposed programming circuit can be integrated into a large array architecture

High-Speed and Energy-Efficient Non-Volatile Silicon Photonic Memory Based on Heterogeneously Integrated Memresonator

Recently, interest in programmable photonics integrated circuits has grown as a potential hardware framework for deep neural networks, quantum computing, and field programmable arrays (FPGAs). However, these circuits are constrained by the limited tuning speed and large power consumption of the phase shifters used. In this paper, introduced for the first time are memresonators, or memristors heterogeneously integrated with silicon photonic microring resonators, as phase shifters with non-volatile memory. These devices are capable of retention times of 12 hours, switching voltages lower than 5 V, an endurance of 1,000 switching cycles. Also, these memresonators have been switched using voltage pulses as short as 300 ps with a record low switching energy of 0.15 pJ. Furthermore, these memresonators are fabricated on a heterogeneous III-V/Si platform capable of integrating a rich family of active, passive, and non-linear optoelectronic devices, such as lasers and detectors, directly on-chip to enable in-memory photonic computing and further advance the scalability of integrated photonic processor circuits

Memristor-based hardware and algorithms for higher-order Hopfield optimization solver outperforming quadratic Ising machines

Ising solvers offer a promising physics-based approach to tackle the challenging class of combinatorial optimization problems. However, typical solvers operate in a quadratic energy space, having only pair-wise coupling elements which already dominate area and energy. We show that such quadratization can cause severe problems: increased dimensionality, a rugged search landscape, and misalignment with the original objective function. Here, we design and quantify a higher-order Hopfield optimization solver, with 28nm CMOS technology and memristive couplings for lower area and energy computations. We combine algorithmic and circuit analysis to show quantitative advantages over quadratic Ising Machines (IM)s, yielding 48x and 72x reduction in time-to-solution (TTS) and energy-to-solution (ETS) respectively for Boolean satisfiability problems of 150 variables, with favorable scaling