Iterative Universal Rigidity

A bar framework determined by a finite graph $G$ and configuration $\bf p$ in $d$ space is universally rigid if it is rigid in any ${\mathbb R}^D \supset {\mathbb R}^d$. We provide a characterization of universally rigidity for any graph $G$ and any configuration ${\bf p}$ in terms of a sequence of affine subsets of the space of configurations. This corresponds to a facial reduction process for closed finite dimensional convex cones.Comment: 41 pages, 12 figure

Study on cash transfers for seed security in humanitarian settings

This study examines the barriers and opportunities for cash transfers to be used to address seed security in humanitarian situations. Cash, while not a new approach, has gained momentum in recent years, especially with the emergence of the Cash Learning Partnership (CaLP) and humanitarian organizations’ commitments through the Grand Bargain.2 Historically, direct seed distribution (DSD) has dominated agricultural responses in emergencies. While effective in many situations, other modalities of addressing farmers’ needs have also proven to be effective, including seed and voucher fairs and, increasingly, cash transfer responses. The latter response typically provides farmers greater choices to make decisions about their seed needs and preferences. However, as with direct distribution and vouchers, cash can be a viable option but may not always be appropriate in every situation. The quality of seed is of paramount importance in choosing a response and has been an ongoing (and often contentious and political) discussion for decades. The results of this study advocate for a multi- stakeholder perspective on the quality of seed, while offering farmers the most flexible and most appropriate response possible for their given situation. In some cases, this will be cash transfers, but certainly not in all cases. A range of options offers the best chance for a successful, responsive, and appropriate program. The evidence base on outcomes from using cash for seed in humanitarian contexts is limited, however, reviewing a series of examples shows the breadth and range of options that are being explored. The cases from an array of organizations and countries including Iraq, Ethiopia, Nigeria, Uganda, Zambia, Zimbabwe, Malawi, Madagascar, and Guatemala, show that understanding the context is key to the response analysis and the choice of modality. Organizational approaches and previous experience also played a role in the choice of modality. The evidence to date shows that cash, in addition to complementary programming such as technical or business training, offers promise for seed security interventions. In addition, initiatives to support both the demand and supply side of the market have proven to be effective. Key findings include: 1. Market and needs assessments must include a seed component or SSSA to ensure a response designed to address the right problem, not the assumption. For markets, both informal and formal seed markets need to be included. 2. Good needs assessments, response analysis and program design help ensure participants’ spending cash on what implementers anticipate they will. 3. Program participants’ preferences on modalities are not consistently included in response analysis. 4. Mixed modalities (cash and vouchers, or cash and DSD) can broaden crop choices. 5. Quality screenings for seed are taking place; the quality of seed is important to organizations and project participants. 6. Cash for seed security interventions are limited, but growing in prevalence. 7. Providing cash plus complementary support is a promising practice for fostering seed security. 8. The nexus between relief and development is critical—designing projects with a longer-term development view: cash can prepare the way for farmers to continue true market engagement post-relief, spur business development in subsequent seasons, and offer opportunities for financial inclusion. 9. Supporting supply side to bring quality seed markets ‘closer’ to project participants should be considered along with demand-side interventions (cash, voucher and other). 10. Investment in preparedness provides a better foundation to implement impactful cash for seed security response. The risks, mitigating actions, opportunities and enablers for cash and seed security response are also explored. The study concludes with actionable and practical recommendations for further advancing the evidence base, as well as implementation suggestions. Continuous collaboration of key stakeholders in seed systems is essential to advance the discussions and action on the way forward with cash and seed systems

Integrated Dynamic Facade Control with an Agent-based Architecture for Commercial Buildings

Dynamic façades have significant technical potential to minimize heating, cooling, and lighting energy use and peak electric demand in the perimeter zone of commercial buildings, but the performance of these systems is reliant on being able to balance complex trade-offs between solar control, daylight admission, comfort, and view over the life of the installation. As the context for controllable energy-efficiency technologies grows more complex with the increased use of intermittent renewable energy resources on the grid, it has become increasingly important to look ahead towards more advanced approaches to integrated systems control in order to achieve optimum life-cycle performance at a lower cost. This study examines the feasibility of a model predictive control system for low-cost autonomous dynamic façades. A system architecture designed around lightweight, simple agents is proposed. The architecture accommodates whole building and grid level demands through its modular, hierarchical approach. Automatically-generated models for computing window heat gains, daylight illuminance, and discomfort glare are described. The open source Modelica and JModelica software tools were used to determine the optimum state of control given inputs of window heat gains and lighting loads for a 24-hour optimization horizon. Penalty functions for glare and view/ daylight quality were implemented as constraints. The control system was tested on a low-power controller (1.4 GHz single core with 2 GB of RAM) to evaluate feasibility. The target platform is a low-cost ($35/unit) embedded controller with 1.2 GHz dual-core cpu and 1 GB of RAM. Configuration and commissioning of the curtainwall unit was designed to be largely plug and play with minimal inputs required by the manufacturer through a web-based user interface. An example application was used to demonstrate optimal control of a three-zone electrochromic window for a south-facing zone. The overall approach was deemed to be promising. Further engineering is required to enable scalable, turnkey solutions

Applying Formal Methods to Networking: Theory, Techniques and Applications

Despite its great importance, modern network infrastructure is remarkable for the lack of rigor in its engineering. The Internet which began as a research experiment was never designed to handle the users and applications it hosts today. The lack of formalization of the Internet architecture meant limited abstractions and modularity, especially for the control and management planes, thus requiring for every new need a new protocol built from scratch. This led to an unwieldy ossified Internet architecture resistant to any attempts at formal verification, and an Internet culture where expediency and pragmatism are favored over formal correctness. Fortunately, recent work in the space of clean slate Internet design---especially, the software defined networking (SDN) paradigm---offers the Internet community another chance to develop the right kind of architecture and abstractions. This has also led to a great resurgence in interest of applying formal methods to specification, verification, and synthesis of networking protocols and applications. In this paper, we present a self-contained tutorial of the formidable amount of work that has been done in formal methods, and present a survey of its applications to networking.Comment: 30 pages, submitted to IEEE Communications Surveys and Tutorial

Evaluator services for optimised service placement in distributed heterogeneous cloud infrastructures

Optimal placement of demanding real-time interactive applications in a distributed heterogeneous cloud very quickly results in a complex tradeoff between the application constraints and resource capabilities. This requires very detailed information of the various requirements and capabilities of the applications and available resources. In this paper, we present a mathematical model for the service optimization problem and study the concept of evaluator services as a flexible and efficient solution for this complex problem. An evaluator service is a service probe that is deployed in particular runtime environments to assess the feasibility and cost-effectiveness of deploying a specific application in such environment. We discuss how this concept can be incorporated in a general framework such as the FUSION architecture and discuss the key benefits and tradeoffs for doing evaluator-based optimal service placement in widely distributed heterogeneous cloud environments

High-Level Object Oriented Genetic Programming in Logistic Warehouse Optimization

Disertační práce je zaměřena na optimalizaci průběhu pracovních operací v logistických skladech a distribučních centrech. Hlavním cílem je optimalizovat procesy plánování, rozvrhování a odbavování. Jelikož jde o problém patřící do třídy složitosti NP-težký, je výpočetně velmi náročné nalézt optimální řešení. Motivací pro řešení této práce je vyplnění pomyslné mezery mezi metodami zkoumanými na vědecké a akademické půdě a metodami používanými v produkčních komerčních prostředích. Jádro optimalizačního algoritmu je založeno na základě genetického programování řízeného bezkontextovou gramatikou. Hlavním přínosem této práce je a) navrhnout nový optimalizační algoritmus, který respektuje následující optimalizační podmínky: celkový čas zpracování, využití zdrojů, a zahlcení skladových uliček, které může nastat během zpracování úkolů, b) analyzovat historická data z provozu skladu a vyvinout sadu testovacích příkladů, které mohou sloužit jako referenční výsledky pro další výzkum, a dále c) pokusit se předčit stanovené referenční výsledky dosažené kvalifikovaným a trénovaným operačním manažerem jednoho z největších skladů ve střední Evropě.This work is focused on the work-flow optimization in logistic warehouses and distribution centers. The main aim is to optimize process planning, scheduling, and dispatching. The problem is quite accented in recent years. The problem is of NP hard class of problems and where is very computationally demanding to find an optimal solution. The main motivation for solving this problem is to fill the gap between the new optimization methods developed by researchers in academic world and the methods used in business world. The core of the optimization algorithm is built on the genetic programming driven by the context-free grammar. The main contribution of the thesis is a) to propose a new optimization algorithm which respects the makespan, the utilization, and the congestions of aisles which may occur, b) to analyze historical operational data from warehouse and to develop the set of benchmarks which could serve as the reference baseline results for further research, and c) to try outperform the baseline results set by the skilled and trained operational manager of the one of the biggest warehouses in the middle Europe.