Stochastic Model Predictive Control for Autonomous Mobility on Demand

This paper presents a stochastic, model predictive control (MPC) algorithm that leverages short-term probabilistic forecasts for dispatching and rebalancing Autonomous Mobility-on-Demand systems (AMoD, i.e. fleets of self-driving vehicles). We first present the core stochastic optimization problem in terms of a time-expanded network flow model. Then, to ameliorate its tractability, we present two key relaxations. First, we replace the original stochastic problem with a Sample Average Approximation (SAA), and characterize the performance guarantees. Second, we separate the controller into two separate parts to address the task of assigning vehicles to the outstanding customers separate from that of rebalancing. This enables the problem to be solved as two totally unimodular linear programs, and thus easily scalable to large problem sizes. Finally, we test the proposed algorithm in two scenarios based on real data and show that it outperforms prior state-of-the-art algorithms. In particular, in a simulation using customer data from DiDi Chuxing, the algorithm presented here exhibits a 62.3 percent reduction in customer waiting time compared to state of the art non-stochastic algorithms.Comment: Submitting to the IEEE International Conference on Intelligent Transportation Systems 201

An introduction to quantum filtering

This paper provides an introduction to quantum filtering theory. An introduction to quantum probability theory is given, focusing on the spectral theorem and the conditional expectation as a least squares estimate, and culminating in the construction of Wiener and Poisson processes on the Fock space. We describe the quantum It\^o calculus and its use in the modelling of physical systems. We use both reference probability and innovations methods to obtain quantum filtering equations for system-probe models from quantum optics.Comment: 41 pages, 1 figur

Localization and parcellation of the supplementary motor area using functional magnetic resonance imaging in frontal tumor patients

Neurosurgery is an effective method for prolonging life and improving outcomes for patients with brain tumors. However, this option bears the risk of damaging areas of eloquent cortex, areas associated with motor and language tasks that, when lesioned, will result in a functional deficit for the patient. Functional magnetic resonance imaging (fMRI) is a valuable tool in the localization of eloquent cortex for preoperative neurosurgical planning. Through use of this modality of functional neuroimaging, the neurosurgeon can adjust the surgical trajectory to incur the least amount of damage to sites of functional activity. The supplementary motor area (SMA) is one such site of eloquent cortex that must be visualized preoperatively due to the risk of postoperative deficit with lesions in this area. However, due to both the effects of tumor pathology and naturally occurring interindividual variability, the SMA’s location and functional fingerprint can be highly variable. We present a study in which patients with frontal tumor (n=46) underwent task-based fMRI for motor and language network mapping. The patient-specific functional data were normalized and evaluated using ROI analysis to illustrate group-level activation patterns within the SMA during the language and motor tasks. The results illustrate a distinct pattern of activation including a rostro-caudal organization of language and motor activation, overlapping extent cluster volumes throughout the two functional subdivisions of the SMA, the pre-SMA and SMA proper, and discrete activation foci

A Case Study on Record Matching of Individuals in Historical Archives of Indigenous Databases

Digitization of historical records has produced a significant amount of data for analysis and interpretation. A critical challenge is the ability to relate historical information across different archives to allow for the data to be framed in the appropriate historical context. This paper presents a real-world case study on historical information integration and record matching with the goal to improve the historical value of archives containing data in the period 1800 to 1920. The archives contain unique information about M\'etis and Indigenous people in Canada and interactions with European settlers. The archives contain thousands of records that have increased relevance when relationships and interconnections are discovered. The contribution is a record linking approach suitable for historical archives and an evaluation of its effectiveness. Experimental results demonstrate potential for discovering historical linkage with high precision enabling new historical discoveries.Comment: Published in 20th International Conference on Information & Knowledge Engineering (IKE'21

How to leverage outward FDI for development? A six-step guide for policymakers

OFDI can increasingly serve as an additional channel for countries to achieve their development goals. This Perspective proposes a six-step framework to help policymakers think through how best to facilitate, support and promote OFDI to maximize the benefits for the home economy

A discrete invitation to quantum filtering and feedback control

The engineering and control of devices at the quantum-mechanical level--such as those consisting of small numbers of atoms and photons--is a delicate business. The fundamental uncertainty that is inherently present at this scale manifests itself in the unavoidable presence of noise, making this a novel field of application for stochastic estimation and control theory. In this expository paper we demonstrate estimation and feedback control of quantum mechanical systems in what is essentially a noncommutative version of the binomial model that is popular in mathematical finance. The model is extremely rich and allows a full development of the theory, while remaining completely within the setting of finite-dimensional Hilbert spaces (thus avoiding the technical complications of the continuous theory). We introduce discretized models of an atom in interaction with the electromagnetic field, obtain filtering equations for photon counting and homodyne detection, and solve a stochastic control problem using dynamic programming and Lyapunov function methods.Comment: 76 pages, 12 figures. A PDF file with high resolution figures can be found at http://minty.caltech.edu/papers.ph

Efficient synthesis of L-lactic acid from glycerol by metabolically engineered Escherichia coli

Due to its abundance and low-price, glycerol has become an attractive carbon source for the industrial production of value-added fuels and chemicals. This work reports the engineering of E. coli for the efficient conversion of glycerol into L-lactic acid(L-lactate). Escherichia coli strains have previously been metabolically engineered for the microaerobic production of D-lactic acid from glycerol in defined media by disrupting genes that minimize the synthesis of succinate, acetate, and ethanol, and also overexpressing the respiratory route of glycerol dissimilation (GlpK/GlpD). Here, further rounds of rationale design were performed on these strains for the homofermentative production of L-lactate, not normally produced in E. coli. Specifically, L-lactate production was enabled by: 1), replacing the native D-lactate specific dehydrogenase with Streptococcus bovis L-lactate dehydrogenase (L-LDH), 2) blocking the methylglyoxal bypass pathways to avoid the synthesis of a racemic mixture of D- and L-lactate and prevent the accumulation of toxic intermediate, methylglyoxal, and 3) the native aerobic L-lactate dehydrogenase was blocked to prevent the undesired utilization of L-lactate. The engineered strain produced 50 g/L of L-lactate from 56 g/L of crude glycerol at a yield 93% of the theoretical maximum and with high optical (99.9%) and chemical (97%) purity. This study demonstrates the efficient conversion of glycerol to L-lactate, a microbial process that had not been reported in the literature prior to our work. The engineered biocatalysts produced L-lactate from crude glycerol in defined minimal salts medium at high chemical and optical purity