Kinetic models identification for the catalytic synthesis of formaldehyde through the partial oxidation of methanol

The availability of solid kinetic models is fundamental for simulating and optimising all the energy systems involving combustion. The identification of a trustworthy model always relies on the collection of valuable information from the experiments, which have to be carefully designed. In this work, tools developed in MBDoE theories are employed to identify a model for the catalytic oxidation of methanol (analogous to the combustion reactions exploited for energetic purposes)

Distribution and habitat use of a recently discovered population of Humboldt martens in California

The Humboldt marten (Martes caurina humboldtensis) has declined from over 95% of its historic range in California, with only two populations remaining. In response to the forthcoming listing of the Humboldt marten a conservation assessment and strategy was developed to address the most important conservation needs for this species. This assessment identified an area near the California – Oregon border as the second extant population area in California based on a small number of recent detections. However little else was known of this population, and this prompted my investigation to determine 1) the distribution and potential population size and 2) habitat use by Humboldt martens in this area. This study addresses a key information need identified in the conservation strategy. Between May – August of 2017 and 2018, I used a 2-km systematic grid to sample 51 sample units using baited remote cameras and track plates and detected martens at 20 (39.2 %) sample units. Using an occupancy modeling approach, I found that a combination of elevation and amount of forest habitat with large diameter trees (size class 5, ≥ 60.0 cm QMD) measured at the home range scale (1-km radius, 314 ha) influenced marten occupancy. Marten occupancy was highest in low elevation sample units (mean = 614.6 m, SE = 35.6 m) with an average of 65.3 ha (20.1% of 314 ha, SE = 12.0 ha) of forest habitat in the largest tree size class. The limited number of detections precluded evaluating models with \u3e 3 habitat variables, as well as assessing finer scale habitat use; however, univariate results suggested stream density may also be influential at the home range scale. Consistent with results from the larger California population, managers interested in promoting marten conservation in the California – Oregon extant population area should maintain and increase large patches of forest habitat with large-diameter trees. A novel finding for this population was the importance of low-elevation forest habitat dominated by size class 4 (27.9 – 59.9 cm QMD), suggesting the combination of home-range sized areas with these two habitat compositions is capable of supporting marten occupancy in this region

Design prototyping methods

textProduct development is often modeled as a cycle between phases of designing, building, and testing. This work will explore early stage build efforts of product design, which is also known as prototyping. Prototyping is a critical determinant of product success. Research shows that different approaches to prototyping can greatly affect design outcome. This work provides an integrated overview, and expansion of the existing work on design prototyping methods. Following the introduction, an extensive literature review of design prototyping tools, techniques, and methods is provided. These sources are indexed and comparatively reviewed. The capabilities of a novel hybrid prototyping technique is explored through a design case study. Next, insights from the review are integrated in a context independent prototyping strategy method. The method is developed with heuristics extracted from the literature, and additional insights from experimental studies. The technique is then experimentally evaluated. Finally, results of an extensive study of an online design repository are provided. The results include five key principles for prototype design and fabrication. The presence of these principles in the repository is validated through a novel crowd-sourced online study. The outcome effects of deploying these principles to design teams is experimentally evaluated. Overall, this research provides a guide to prototyping which includes a systematically indexed review and comparison of the existing work, as well as a novel method, and principles for design and fabrication.Mechanical Engineerin

Passive Micromixers

Micro-total analysis systems and lab-on-a-chip platforms are widely used for sample preparation and analysis, drug delivery, and biological and chemical syntheses. A micromixer is an important component in these applications. Rapid and efficient mixing is a challenging task in the design and development of micromixers. The flow in micromixers is laminar, and, thus, the mixing is primarily dominated by diffusion. Recently, diverse techniques have been developed to promote mixing by enlarging the interfacial area between the fluids or by increasing the residential time of fluids in the micromixer. Based on their mixing mechanism, micromixers are classified into two types: active and passive. Passive micromixers are easy to fabricate and generally use geometry modification to cause chaotic advection or lamination to promote the mixing of the fluid samples, unlike active micromixers, which use moving parts or some external agitation/energy for the mixing. Many researchers have studied various geometries to design efficient passive micromixers. Recently, numerical optimization techniques based on computational fluid dynamic analysis have been proven to be efficient tools in the design of micromixers. The current Special Issue covers new mechanisms, design, numerical and/or experimental mixing analysis, and design optimization of various passive micromixers

Sensors Application in Agriculture

Novel technologies are playing an important role in the development of crop and livestock farming and have the potential to be the key drivers of sustainable intensification of agricultural systems. In particular, new sensors are now available with reduced dimensions, reduced costs, and increased performances, which can be implemented and integrated in production systems, providing more data and eventually an increase in information. It is of great importance to support the digital transformation, precision agriculture, and smart farming, and to eventually allow a revolution in the way food is produced. In order to exploit these results, authoritative studies from the research world are still needed to support the development and implementation of new solutions and best practices. This Special Issue is aimed at bringing together recent developments related to novel sensors and their proved or potential applications in agriculture

Experimental Study on Transient Behavior of Water and Nanofluid in Multiport Slab Minichannel Heat Exchangers

Heat exchangers are essential components of many systems and their use is extended to include various industrial, chemical, and automotive applications. A dynamic response study of a heat exchanger is essential for better representation of its design, selection, and analysis as it operates in conjunction with other process equipment. This study aims to experimentally investigate the transient performance of compact heat exchangers. A wide-range well prepared experimental setup is designed and assembled to examine the transient behavior of various types of cross-flow liquid to air heat exchangers. This set up is capable of stepping up or down the temperatures and flow rates for both hot and cold fluids covering a broad range of perturbations that occur in transient scenarios. A step function is a close approximation of a transient variation in heat exchangers, therefore, this work examines the transient response of both fluids under hot liquid side step changes in mass flow from 0.5 to 2.5, and inlet temperature from 1.5 to 3.5 while air inlet conditions are kept constant. Results are presented in terms of transient dimensional and non-dimensional outlet responses of fluids temperatures, heat transfer rates, heat balance, normalized outlet temperatures, and effectiveness. The current experimental findings provide an overview of the characteristic behavior of specific parameters such as response time, initial delay and time constant of both fluids. A comparison of the results obtained is made with the limited experimental work found in the literature. It is observed that the response time is faster for both fluids with the increase of the mass and temperature perturbations and it is higher for the hot liquid than the cold air side. An adverse trend is found between the hot and cold fluids’ effectiveness in temperature step changes, while the same trend is found in mass flow steps. Mass flow step changes for positive and negative steps exhibit an asymmetric trend of both fluids. This work also examines the transient effect of using an engineered fluid, such as Al2O3/water nanofluid, in heat exchangers due to their improved thermophysical properties. The nanofluid is analyzed in terms of its particle size distribution, chemical characterization, and agglomeration of suspensions using the Transmission electron microscopy (TEM), Energy- Dispersive Spectrometry (EDS) and Dynamic light scattering (DLS). Experimental results show that the response time of the nanofluid for the temperature and mass flow steps are faster compared to water. An increase of up to 19% in heat transfer rate is observed when using nanofluid. A comparison of the dynamic performance of a minichannel heat exchanger and a conventional radiator using step variations in inlet liquid temperature and mass flow rate is investigated. Results show longer response time for the conventional radiator compared to the minichannel heat exchanger. In addition, the analytical model for transient heat exchanger response is assessed with the non-dimensional outlet temperature response of a traditional tube and fin heat exchanger subjected to mass flow step changes. A more than 20% overestimate prediction is found for the transient temperature responses using the analytical model. The Empirical correlations developed for temperature and mass flow rate steps are found in a good agreement with the experimental data. The conclusion reached in this study provides an insight on the transient behavior of conventional and minichannel heat exchangers under liquid mass flow and temperatures steps. This experimental work is used to further establish and enrich a database for future advances on the dynamic response of heat exchangers subjected to step changes in liquid inlet conditions

Innovative surveying methodologies through Handheld Terrestrial LIDAR Scanner technologies for forest resource assessment

Precision Forestry is an innovative sector that is currently of great importance for forest and spatial planning. It enables complex analyses of forest data to be carried out in a simple and economical way and facilitates collaboration between technicians, industry operators and stakeholders, thus ensuring transparency in forestry interventions (Corona et al., 2017). The principles of "Precision Forestry" are to use modern tools and technologies with the aim to obtain as much real information as possible, to improve decision-making, and to ensure the current objectives of forest management. Thanks to the rapid technological developments in remote sensing during the last few decades, there have been remarkable improvements in measurement accuracy, and consequentially improvements in the quality of technical elaborations supporting planning decisions. During this period, several scientific publications have demonstrated the potential of the LIDAR system for measuring and mapping forests, geology, and topography in large-scale forest areas. The LIDAR scans obtained from the TLS and HLS systems provide detailed information about the internal characteristics of tree canopys, making them an essential tool for studying stem allometry, volume, light environments, photosynthesis, and production models. In light of these considerations, this thesis aims to expand the current knowledge on the terrestrial LIDAR system applications for monitoring forest ecosystems and dynamics by providing insight on the feasibility and effectiveness of these systems for forest planning. In particular, this study fills a gap in the literature regarding practical examples of the use of innovative technologies in forestry. The main themes of this work are: A) The strengths and weaknesses of the mobile LIDAR system for a forest company; B) The applicability and versatility of the LIDAR HLS tool for sustainable forest management applications; C) Single tree analysis from HLS LIDAR data.   To investigate these themes, we analyzed six cases studies: 1) An investigation of the feasibility and efficiency of LIDAR HLS scanning for an accurate estimation of forest structural attributes by comparing scans using the LIDAR HLS survey method (Handheld Mobile Laser Scanner) to traditional instruments; 2) An examination of walking scan path density’s influence on single-tree attribute estimation by HMLS, taking into account the structural biodiversity of two forest ecosystems under examination, and an estimation of the cost-effectiveness of each type of laser survey based on the path scheme considered; 3) A study of how LIDAR HLS surveys can contribute to fire prevention interventions by providing a quantitative classification of fuels and a preliminary description of the structural and spatial development of the forest in question; 4) An application of a method for assessing and rating stem straightness in tree posture using LIDAR HLS surveys to quantify differences between stands of different log qualities; 5) The identification of features of a Mediterranean old-growth forest using LIDAR HLS surveys according to the criteria established in the literature; 6) The extrapolation of dimensional information for Ficus macrophylla subsp. columnaris to identify the monumental character of the tree by comparing the most appropriate LIDAR HLS point cloud processing methodologies and estimating the total volume of individual trees. In conclusion, the results of these cases studies are useful to determine new research aspects within the system in the forest environment by applying recently published analysis methodologies and indications of relevant terrestrial LIDAR methodologies

Precise single cell monitoring reveals principles of cell growth

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 104-107).Accumulation of mass is a fundamental cellular process that is associated with metabolism, signaling and regulation. Despite the wealth of knowledge in molecular processes the principles of growth in mammalian cells are poorly understood since growth has never been monitored with high precision. Development of the Suspended Microchannel Resonator (SMR), a microfluidic mass measurement system, enables femtogram cell mass resolution. With this, we developed a method to simultaneously measure molecular signals and single cell mass with high precision over multiple generations. First we investigated how cells control their size. It is known that proliferating cells govern the rate at which they build their biomass and divide, but the mechanism that is used to maintain size homeostasis remains unclear. We obtained over 1,000 hours of growth data from mouse lymphoblast and pro-B-cell lymphoid cell lines. Cell lineage analysis revealed a decrease in the growth rate variability at the G1/S phase transition, which suggests the presence of a growth rate threshold for maintaining size homeostasis. We could also identify unexpected aspects of the growth trajectory such as continuation of growth during M phase, large and switch-like drop in growth rate upon cytokinesis. We next studied the metabolic and energetic requirements necessary for cell growth by monitoring immediate single cell growth response to nutrient depletion. To this end, we developed a method to gently exchange the fluid surrounding a cell while constantly monitoring cell growth. We observed that cells immediately change the growth rate upon depletion of key nutrients such as glucose or glutamine. The growth rate change was surprisingly large but restored upon repletion of nutrients. This implies that immediate growth response integrates both loss of nutrient uptake and signaling associated with metabolism of the particular nutrient. We developed two platforms to measure single cell growth in high throughput. These advancements will broaden the application of the SMR to the study of primary cells or cancer cells.by Sungmin Son.Ph.D

Bio-Inspired Robotics

Modern robotic technologies have enabled robots to operate in a variety of unstructured and dynamically-changing environments, in addition to traditional structured environments. Robots have, thus, become an important element in our everyday lives. One key approach to develop such intelligent and autonomous robots is to draw inspiration from biological systems. Biological structure, mechanisms, and underlying principles have the potential to provide new ideas to support the improvement of conventional robotic designs and control. Such biological principles usually originate from animal or even plant models, for robots, which can sense, think, walk, swim, crawl, jump or even fly. Thus, it is believed that these bio-inspired methods are becoming increasingly important in the face of complex applications. Bio-inspired robotics is leading to the study of innovative structures and computing with sensory–motor coordination and learning to achieve intelligence, flexibility, stability, and adaptation for emergent robotic applications, such as manipulation, learning, and control. This Special Issue invites original papers of innovative ideas and concepts, new discoveries and improvements, and novel applications and business models relevant to the selected topics of ``Bio-Inspired Robotics''. Bio-Inspired Robotics is a broad topic and an ongoing expanding field. This Special Issue collates 30 papers that address some of the important challenges and opportunities in this broad and expanding field