Motion Planning of Uncertain Ordinary Differential Equation Systems

This work presents a novel motion planning framework, rooted in nonlinear programming theory, that treats uncertain fully and under-actuated dynamical systems described by ordinary differential equations. Uncertainty in multibody dynamical systems comes from various sources, such as: system parameters, initial conditions, sensor and actuator noise, and external forcing. Treatment of uncertainty in design is of paramount practical importance because all real-life systems are affected by it, and poor robustness and suboptimal performance result if it’s not accounted for in a given design. In this work uncertainties are modeled using Generalized Polynomial Chaos and are solved quantitatively using a least-square collocation method. The computational efficiency of this approach enables the inclusion of uncertainty statistics in the nonlinear programming optimization process. As such, the proposed framework allows the user to pose, and answer, new design questions related to uncertain dynamical systems. Specifically, the new framework is explained in the context of forward, inverse, and hybrid dynamics formulations. The forward dynamics formulation, applicable to both fully and under-actuated systems, prescribes deterministic actuator inputs which yield uncertain state trajectories. The inverse dynamics formulation is the dual to the forward dynamic, and is only applicable to fully-actuated systems; deterministic state trajectories are prescribed and yield uncertain actuator inputs. The inverse dynamics formulation is more computationally efficient as it requires only algebraic evaluations and completely avoids numerical integration. Finally, the hybrid dynamics formulation is applicable to under-actuated systems where it leverages the benefits of inverse dynamics for actuated joints and forward dynamics for unactuated joints; it prescribes actuated state and unactuated input trajectories which yield uncertain unactuated states and actuated inputs. The benefits of the ability to quantify uncertainty when planning the motion of multibody dynamic systems are illustrated through several case-studies. The resulting designs determine optimal motion plans—subject to deterministic and statistical constraints—for all possible systems within the probability space

Simultaneous Optimal Uncertainty Apportionment and Robust Design Optimization of Systems Governed by Ordinary Differential Equations

The inclusion of uncertainty in design is of paramount practical importance because all real-life systems are affected by it. Designs that ignore uncertainty often lead to poor robustness, suboptimal performance, and higher build costs. Treatment of small geometric uncertainty in the context of manufacturing tolerances is a well studied topic. Traditional sequential design methodologies have recently been replaced by concurrent optimal design methodologies where optimal system parameters are simultaneously determined along with optimally allocated tolerances; this allows to reduce manufacturing costs while increasing performance. However, the state of the art approaches remain limited in that they can only treat geometric related uncertainties restricted to be small in magnitude. This work proposes a novel framework to perform robust design optimization concurrently with optimal uncertainty apportionment for dynamical systems governed by ordinary differential equations. The proposed framework considerably expands the capabilities of contemporary methods by enabling the treatment of both geometric and non-geometric uncertainties in a unified manner. Additionally, uncertainties are allowed to be large in magnitude and the governing constitutive relations may be highly nonlinear. In the proposed framework, uncertainties are modeled using Generalized Polynomial Chaos and are solved quantitatively using a least-square collocation method. The computational efficiency of this approach allows statistical moments of the uncertain system to be explicitly included in the optimization-based design process. The framework formulates design problems as constrained multi-objective optimization problems, thus enabling the characterization of a Pareto optimal trade-off curve that is off-set from the traditional deterministic optimal trade-off curve. The Pareto off-set is shown to be a result of the additional statistical moment information formulated in the objective and constraint relations that account for the system uncertainties. Therefore, the Pareto trade-off curve from the new framework characterizes the entire family of systems within the probability space; consequently, designers are able to produce robust and optimally performing systems at an optimal manufacturing cost. A kinematic tolerance analysis case-study is presented first to illustrate how the proposed methodology can be applied to treat geometric tolerances. A nonlinear vehicle suspension design problem, subject to parametric uncertainty, illustrates the capability of the new framework to produce an optimal design at an optimal manufacturing cost, accounting for the entire family of systems within the associated probability space. This case-study highlights the general nature of the new framework which is capable of optimally allocating uncertainties of multiple types and with large magnitudes in a single calculation

Dynamic Optimization on Quantum Hardware: Feasibility for a Process Industry Use Case

The quest for real-time dynamic optimization solutions in the process industry represents a formidable computational challenge, particularly within the realm of applications like model predictive control where rapid and reliable computations are critical. Conventional methods can struggle to surmount the complexities of such tasks. Quantum computing and quantum annealing emerge as avant-garde contenders to transcend conventional computational constraints. We convert a dynamic optimization problem, characterized by a system of differential equations, into a Quadratic Unconstrained Binary Optimization problem, enabling quantum computational approaches. The empirical findings synthesized from classical methods, simulated annealing, quantum annealing via D-Wave's quantum annealer, and hybrid solver methodologies, illuminate the intricate landscape of computational prowess essential for tackling complex and high-dimensional dynamic optimization problems. Our findings suggest that while quantum annealing is a maturing technology that currently does not outperform state-of-the-art classical solvers, continuous improvements could eventually aid in increasing efficiency within the chemical process industry.Comment: 17 pages, 5 figure

A Bio-Inspired Tensegrity Manipulator with Multi-DOF, Structurally Compliant Joints

Most traditional robotic mechanisms feature inelastic joints that are unable to robustly handle large deformations and off-axis moments. As a result, the applied loads are transferred rigidly throughout the entire structure. The disadvantage of this approach is that the exerted leverage is magnified at each subsequent joint possibly damaging the mechanism. In this paper, we present two lightweight, elastic, bio-inspired tensegrity robotics arms which mitigate this danger while improving their mechanism's functionality. Our solutions feature modular tensegrity structures that function similarly to the human elbow and the human shoulder when connected. Like their biological counterparts, the proposed robotic joints are flexible and comply with unanticipated forces. Both proposed structures have multiple passive degrees of freedom and four active degrees of freedom (two from the shoulder and two from the elbow). The structural advantages demonstrated by the joints in these manipulators illustrate a solution to the fundamental issue of elegantly handling off-axis compliance.Comment: IROS 201

Saving CO2 Emissions by Reusing Organic Growing Media from Hydroponic Tomato Production as a Source of Nutrients to Produce Ethiopian Kale (Brassica carinata)

Large quantities of growing media residues that are rich in nutrients are disposed of after their use in hydroponics. The objective of this study was to investigate the benefits of different organic growing media (wood fibers, hemp fibers, sphagnum moss) residues from hydroponic tomato production as a nutrient source to produce Ethiopian kale. The amount of nutrients that can be reused as fertilizer and the associated CO2 savings have been calculated. Kale was cultivated in sand-residue mixtures, either with 25 or 50 vol% of the mentioned growing media residues. Control treatments with sand with or without nutrient addition were cultivated too. The incorporation of all growing media residues to sand increased the field capacity and growth. Plants that were supplemented with hemp fiber residues showed the strongest growth and highest yields. However, the hemp fiber residues that are used are not suitable for use in the open field due to its excessive content of certain nutrients, which restrict the output quantity. Regarding the fertilization effect of growing media residues, it was calculated that 11–300 kg nutrients ha−1 (N, P, K, Mg, Ca, S), with an average primary energy demand of 90–3435 MJ and 6–317 kg CO2 eq, could potentially be saved when different crops were considered.Peer Reviewe

Toward Innovative, Liveable, and Prosperous Asian Megacities: The University of the Philippines - Ayala Land Technology Hub

A city innovation is a new solution that creates additional value to people in the city by addressing urban challenges. This could be in terms of technological, institutional, organizational, political, economic and social, as long as it creates value to the city’s prosperity, liveability, and social equity. The UP-Ayala Technology Hub fosters a city innovation in the heart of Quezon City. The UP-Ayala Technology Hub is a pioneer on academically-based IT Park in the Philippines that was created to face challenges of competition and economic development. This provides an area in which small-scale businesses could grow their operations through promoting industry and academe linkages. Moreover, this impacts the growth of the city from the typical residential area to introducing a business complex which caters to start-up and medium-scale businesses

Longitudinal associations among relationship factors, partner change, and sexually transmitted infection acquisition in adolescent women

OBJECTIVES: New sex partners put adolescents at increased risk for sexually transmitted infections (STIs), even when these sex partners are nonoverlapping. Although the risk of partner change is well described, little is known about its antecedents. We prospectively examined associations between relationship characteristics, partner change, and subsequent STI during intervals of "serial monogamy." METHODS: As part of a longitudinal study, 332 adolescent women were interviewed and tested for gonorrhea, chlamydia, and trichomonas every 3 months for up to just over 6 years. Interviews covered partner-specific relationship characteristics and sexual behaviors. The quarterly interval, a 3-month period bracketed by interviews and STI testing, was the unit of analysis. We examined associations among relationship factors, partner change, and subsequent STI using a series of mixed regression models, controlling for age, STI at Time 1, and condom nonuse. RESULTS: Age, lower relationship quality, and lower levels of partner closeness to friends and family predicted partner change from Time 1 to Time 2. In turn, partner change was associated with acquisition of a new STI at Time 2. Although relationship factors did not exert a direct effect on STI at Time 2, they improved partner change-STI model fit. Similar patterns were seen with each organism. CONCLUSION: Relationship factors drive partner change, which in turn contributes to STI acquisition. STI prevention research may need to focus on the relationship antecedents to partner change, in addition to the partner change itself

Chromosomal integration vectors allowing flexible expression of foreign genes in Campylobacter jejuni.

BACKGROUND: Campylobacter jejuni is a major cause of human gastroenteritis yet there is limited knowledge of how disease is caused. Molecular genetic approaches are vital for research into the virulence mechanisms of this important pathogen. Vectors that allow expression of genes in C. jejuni via recombination onto the chromosome are particularly useful for genetic complementation of insertional knockout mutants and more generally for expression of genes in particular C. jejuni host backgrounds. METHODS: A series of three vectors that allow integration of genes onto the C. jejuni chromosome were constructed by standard cloning techniques with expression driven from three different strong promoters. Following integration onto the C. jejuni chromosome expression levels were quantified by fluorescence measurements and cells visualized by fluorescence microscopy. RESULTS: We have created plasmid, pCJC1, designed for recombination-mediated delivery of genes onto the C. jejuni chromosome. This plasmid contains a chloramphenicol resistance cassette (cat) with upstream and downstream restriction sites, flanked by regions of the C. jejuni pseudogene Cj0223. Cloning of genes immediately upstream or downstream of the cat gene allows their subsequent introduction onto the C. jejuni chromosome within the pseudogene. Gene expression can be driven from the native gene promoter if included, or alternatively from the cat promoter if the gene is cloned downstream of, and in the same transcriptional orientation as cat. To provide increased and variable expression of genes from the C. jejuni chromosome we modified pCJC1 through incorporation of three relatively strong promoters from the porA, ureI and flaA genes of C. jejuni, Helicobacter pylori and Helicobacter pullorum respectively. These promoters along with their associated ribosome binding sites were cloned upstream of the cat gene on pCJC1 to create plasmids pCJC2, pCJC3 and pCJC4. To test their effectiveness, a green fluorescent protein (gfp) reporter gene was inserted downstream of each of the three promoters and following integration of promoter-gene fusions onto the C. jejuni host chromosome, expression levels were quantified. Expression from the porA promoter produced the highest fluorescence, from flaA intermediate levels and from ureI the lowest. Expression of gfp from the porA promoter enabled visualization by fluorescent microscopy of intracellular C. jejuni cells following invasion of HeLa cells. CONCLUSIONS: The plasmids constructed allow stable chromosomal expression of genes in C. jejuni and, depending on the promoter used, different expression levels were obtained making these plasmids useful tools for genetic complementation and high level expression

Low-Carbon Innovation in China: Prospects, Politics and Practices - Innovation

China’s potential transition to a low-carbon, climate resilient or ‘post-carbon’ society is a key concern for the world. There is an urgent need for better understanding of this process, posing major challenges for social science given the complex, systemic and emergent nature of the multiple processes involved in such a possible transition. This Working Paper is the first of a series of four 'China Low Carbon Reports' outlining the STEPS-Centre affiliate project 'Low Carbon Innovation in China: Prospects, Politics and Practice', led from Lancaster University. The project is designed around problem-led social scientific research involving partners from leading UK and Chinese institutions. It aims to assess the status of, and opportunities for, low-carbon transitions in China by going beyond existing technology-focused approaches to innovation. In particular, this involves a re-insertion and reconceptualisation of power within the processes of low-carbon transitions, conceived as processes of socio-technical systems, and with greater attention paid to everyday social practices of both ‘users’ and producers. Through this distinct approach, the project offers empirical, methodological and theoretical contributions to the study of (low-carbon) socio-technical transitions both in China and more broadly. The paper outlines the background to this project, the urgency of deeper and more productive understanding of the prospects of low-carbon transition in China, and the theoretical and methodological approaches adopted to do this

Evaluation of bast fibre retting systems on hemp

In this paper the effect of eight different retting methods on decorticated hemp skins were analyzed. The methods were taken from six publications that looked at the retting of different bast fibres such as ramie, flax and kenaf. The fibres were batch retted in a package dye-vat at 100oC under 2 bar of pressure. The rinsed fibres were opened twice using a Shirley cotton trash separator. The opened fibre was assessed for fibre width, fibre width variation, colour and handle. It was found that the fibre that had undergone chemical retting with 7% Sodium Hydroxide (NaOH) and 0.5% Sodium Sulphite (Na2SO3) had the best diameter (18.39 micron) and the best coefficient of variation of diameter (57.32%). The fibre that was processed with 7% Sodium Hydroxide (NaOH) and 0.5% Sodium Sulphite (Na2SO3) had the whitest colour (YI D1925 = 31.61). The method treated with 1% Sodium Hydroxide (NaOH) and 1% Sodium Sulphite (Na2SO3) had the softest handle and the method treated with 1% Sodium Hydroxide (NaOH) and pre-rinsed with 0.3% Hydrochloric Acid (HCl) showed the best conversion of decorticated skins into spin able fibre (33.9% of dry green skins). It was decided that method treated with 1% Sodium Hydroxide (NaOH) and pre-rinsed with 0.3% Hydrochloric Acid (HCl) had the best fineness of fibre micron, conversion to spin able fibre (33.9% of dry green skins), whitest colour (YI D1925 = 36.13) and softest handle for the cost of chemicals involved.<br /