Assessing the structural complexity of manufacturing systems configurations

Modern manufacturing systems are increasingly required to be flexible and adaptable to changing market demands, which adds to their structural and operational complexity. One of the major challenges at the early design stages is to select a manufacturing system configuration that both satisfies the production functional requirements and is easy to operate and manage. A new metric for assessing the structural complexity of manufacturing system configurations is presented in this paper. The proposed complexity metric incorporates the quantity of information using an entropy approach. It accounts for the complexity inherent in the various modules in the manufacturing system through the use of an index derived from a newly developed manufacturing systems classification code. The code captures the effect of various component types and technologies used in a manufacturing system on the system’s structural complexity. The presented metric would be helpful in selecting the least complex manufacturing system configuration that meets the requirements. An engine cylinder head production system is used to illustrate the application of the proposed methodology in comparing feasible but different manufacturing system configurations capable of producing the cylinder head based on their structurally inherent complexity.     

Feeding Mechanisms in Sharks

Although many sharks have a rather general vertebrate body plan,they display a number of specializations for feeding that beliethe notion that they are "primitive." These specializationsinclude a battery of highly developed exteroceptive systemssuch as vision, olfaction, acoustico-lateralis sense and electroreception;and a cranial morphology that has been molded into a numberof functionally adaptive forms. These forms result in grasping,sucking, crushing, gouging, cutting and filtering systems offeeding. With relatively few exceptions elasmobranch feedingmechanisms share such features as subterminal or inferior mouths,a dynamic tooth replacement system, hyostylic jaw suspensionand a kinetic, protractile upper jaw. The importance of eachof these components is discussed. The evolution of the highdiversity of mechanical feeding systems in such a small groupof vertebrates has probably been facilitated by the morphologicalsimplicity of the basic feeding mechanism. This radiation wasaccomplished by modifications in jaw length, the length andsupporting angle of the hyomandibula, the size of the gape,dentition and changes in the relative size of the cranial musculature.The evolutionary pattern of shark feeding mechanisms is complex,there being several examples of both parallelism and convergence.A long-jawed, grasping form (similar to, but not identical withChlamydoselachus) is here considered primitive. From a subsequentbenthic sucking and grasping ancestor, similar in many respectsto some living batoids,radiated crushing, ray-like forms; cutting,squaloid forms; and gouging, lamniform and carcharhiniform types.From the latter developed sucking and grasping, or crushingforms such as modern orectolobiforms, triakids and heterodontiformsharks. From several levels (primary crushing, secondary crushingand gouging) there emerged filter-feeding forms representedtoday by mobulids, rhiniodontids and cetorhin.     

Combining a Geographical Information System and Process Engineering to Design an Agricultural-Industrial Ecosystem

A methodology to systematically construct an industrial ecosystem is presented in the context of a specific biomass input of peanut hulls and a process complex of activated carbon, adhesive precursor, and hydrogen. The methodology consists of three phases: locating sources and sinks of potential materials for exchange or upgrading; filtering feasible exchanges, the exchange candidates, and locations for new infrastructure; and generating optimal configurations for the industrial ecosystem based on the objective of maximizing the system benefit, defined in the particular case study as the revenue that is generated by the system. To implement the methodology two computer tools are combined: geographic information systems (GIS) and mathematical programming. A screening problem formulation is developed that uses feasibility contours to help reduce the number of candidate material and energy linkages. A case study describing a prospective agro-industrial complex in the state of Georgia, U.S.A., is given.     

The effect of age at metamorphosis on the transition from larval to adult suspension‐feeding of the slipper limpet Crepidula fornicata

Slipper limpets use different ciliary feeding mechanisms as larvae and adults. Veliger larvae of Crepidula fornicata developed part of the adult feeding apparatus, including ctenidial filaments, neck lobe, and radula, before metamorphosis, but ctenidial feeding did not begin until well after loss of the larval feeding apparatus (velum) at metamorphosis. Earlier initiation of ctenidial feeding by individuals that were older larvae when metamorphosis occurred suggests continued development toward ctenidial feeding during delay of metamorphosis. Early juveniles produced a ciliary current through the mantle cavity and moved the radula in a grasping action before they began to capture algal cells on mucous strands or form a food cord. Either early juveniles could not yet form mucous strands or they delayed their production until development of other necessary structures. The neck canal for transporting food from ctenidium to mouth cannot develop before velar loss. In their first feeding, juveniles fed much like the adults except that the neck canal was less developed and the path of the food cord toward the mouth sometimes varied. As suspension feeders, calyptraeids lack the elaborations of foregut that complicate transition to juvenile feeding for many caenogastropods, but a path for the food cord must develop after velar loss. Why individuals can initiate ctenidial feeding sooner when they are older at metamorphosis is not yet known. The juveniles became sedentary soon after metamorphosis and were not observed to feed by scraping the substratum with the radula, in contrast to the first feeding by juveniles of another calyptraeid species, observed by Montiel et al. ( 2005 ).     

Dynamic modeling and optimal fed-batch feeding strategies for a two-phase partitioning bioreactor

A dynamic model for the degradation of phenol in a two-phase partitioning bioreactor has been developed based on mechanistic balances around the bioreactor. The key process characteristics including substrate transfer between the organic and aqueous phases, substrate inhibition, oxygen limitation, and cell entrainment were incorporated into the model. The model predictions were validated against existing experimental data obtained for a 2-L bioreactor, and good correlation was observed for the time frames of the simulations, as well as for trends in cell and substrate concentrations. Optimal fed-batch, phenol feeding strategies were then developed based on two approaches: (1) maximization of phenol consumption in a fixed time interval and (2) consumption of a fixed amount of phenol in minimal time. The optimal feeding policies, determined using the Iterative Dynamic Programming algorithm, provided substantial improvements in the amount of phenol consumed when compared to a typical experimental heuristic approach. For example, 45.73 g of phenol was predicted to be consumed in 50 h (not including lag phase) using the optimal feeding profile compared to 10.26 g of phenol consumed in the simulated experimental approach. Oxygen limitation was predicted to be a recurring operational challenge in the partitioning bioreactor, and had a strong impact on the optimization results.     

Assignment of absolute configuration of 3-hydroxy beta-lactams by the NMR "mix and shake" method

The absolute configurations of several 3-hydroxy beta-lactams were assigned by the NMR "mix and shake" methodology developed by Riguera and co-workers. The results from the NMR study correlated perfectly with the absolute configurations obtained from X-ray crystallographic structure analyses and chiral-phase HPLC data.     

Grasping kinematics from the perspective of the individual digits: a modelling study

Grasping is a prototype of human motor coordination. Nevertheless, it is not known what determines the typical movement patterns of grasping. One way to approach this issue is by building models. We developed a model based on the movements of the individual digits. In our model the following objectives were taken into account for each digit: move smoothly to the preselected goal position on the object without hitting other surfaces, arrive at about the same time as the other digit and never move too far from the other digit. These objectives were implemented by regarding the tips of the digits as point masses with a spring between them, each attracted to its goal position and repelled from objects' surfaces. Their movements were damped. Using a single set of parameters, our model can reproduce a wider variety of experimental findings than any previous model of grasping. Apart from reproducing known effects (even the angles under which digits approach trapezoidal objects' surfaces, which no other model can explain), our model predicted that the increase in maximum grip aperture with object size should be greater for blocks than for cylinders. A survey of the literature shows that this is indeed how humans behave. The model can also adequately predict how single digit pointing movements are made. This supports the idea that grasping kinematics follow from the movements of the individual digits.     

Supplementation,stocking rates,and economic performance of lamb production systems in the Mediterranean-type region of Chile

A simulation model was developed and validated to analyze the bioeconomic performance of alternative technologies applied to lamb production systems in the Mediterranean-type rangelands of Central Chile. The model includes consideration of climatic events that affect pasture growth, the nutritive value of the forage on offer, and animal performance as affected by energy and protein intake of directly grazed native pastures and supplements.Model outputs were compared to experimental results and showed excellent agreement in terms of pasture and animal growth. The model was then used to study the bioeconomic consequences of alternative technologies that could improve animal outputs among large commercial-type operations and also in small farms. It was shown that under current price scenarios for inputs and outputs, the only feasible improvement over extant systems was supplementation with modest levels of concentrates, particularly in small farms, and the simulations showed how costs and benefits are modified by lamb prices. A heuristic methodology was developed to search for local economic optima in terms of minimum costs and maximum net income that appears to apply to existing systems better than linear optimization.     

The Narrow Niche hypothesis: gray squirrels shed new light on primate origins

Current hypotheses for primate origins propose that nails and primate-like grasping hands and feet were important early adaptations for feeding in fine branches. Comparative research in this area has focused on instances of convergence in extant animals, showing that species with primate-like morphology feed predominantly from terminal branches. Little has been done to test whether animals without primate-like morphology engage in similar behavior. We tested the fine-branch niche hypothesis for primate origins by observing branch use in Eastern gray squirrels, Sciurus carolinensis, a species lacking primate grasping adaptations that has been understudied in the context of primate origins. We hypothesized that because gray squirrels lack primate-like grasping adaptations, they would avoid feeding and foraging in terminal branches. Instantaneous focal animal sampling was used to examine the locomotor and postural behaviors used while feeding and foraging. Our results demonstrate habitual and effective usage of terminal branches by gray squirrels while feeding and foraging, primarily on tree seeds (e.g., oak, maple, and elm). Discriminant function analysis indicates that gray squirrels feed and forage like primates, unlike some other tree squirrel species. Given the absence of primate-like features in gray squirrels, we suggest that although selection for fine-branch foraging may be a necessary condition for primate origins, it is not sufficient. We propose an alternative model of primate origins. The Narrow Niche hypothesis suggests that the primate morphological suite evolved not only from selection pressure for fine branch use, but also from a lack of engagement in other activities.     

Review: Key tweaks to the chicken's beak: the versatile use of the beak by avian species and potential approaches for improvements in poultry production

The avian beak is a multipurpose organ playing a vital role in a variety of functions, including feeding, drinking, playing, grasping objects, mating, nesting, preening and defence against predators and parasites. With regards to poultry production, the beak is the first point of contact between the bird and feed. The beak is also manipulated to prevent unwanted behaviour such as feather pecking, toe pecking and cannibalism in poultry as well as head/neck injuries to breeder hens during mating. Thus, investigating the beak morphometry of poultry in relation to feeding and other behaviours may lead to novel insights for poultry breeding, management and feeding strategies. Beak morphometry data may be captured by advanced imaging techniques coupled with the use of geometric morphometric techniques. This emerging technology may be utilized to study the effects of beak shape on many critical management issues including heat stress, parasite management, pecking and feeding behaviour. In addition, existing literature identifies several genes related to beak development in chickens and other avian species. Use of morphometric assessments to develop phenotypic data on beak shape and detailed studies on beak-related behaviours in chickens may help in improving management and welfare of commercial poultry.     

Performance of flip supertree construction with a heuristic algorithm

Supertree methods are used to assemble separate phylogenetic trees with shared taxa into larger trees (supertrees) in an effort to construct more comprehensive phylogenetic hypotheses. In spite of much recent interest in supertrees, there are still few methods for supertree construction. The flip supertree problem is an error correction approach that seeks to find a minimum number of changes (flips) to the matrix representation of the set of input trees to resolve their incompatibilities. A previous flip supertree algorithm was limited to finding exact solutions and was only feasible for small input trees. We developed a heuristic algorithm for the flip supertree problem suitable for much larger input trees. We used a series of 48- and 96-taxon simulations to compare supertrees constructed with the flip supertree heuristic algorithm with supertrees constructed using other approaches, including MinCut (MC), modified MC (MMC), and matrix representation with parsimony (MRP). Flip supertrees are generally far more accurate than supertrees constructed using MC or MMC algorithms and are at least as accurate as supertrees built with MRP. The flip supertree method is therefore a viable alternative to other supertree methods when the number of taxa is large.     

A KINEMATIC STUDY OF SUCTION FEEDING AND ASSOCIATED BEHAVIOR IN THE LONG-FINNED PILOT WHALE, GLOBICEPHALA MELAS (TRAILL)

Analysis of videotaped feeding sequences provides novel documentation of suction feeding in captive juvenile long-finned pilot whales ( Globicephala melas ). Swimming and stationary whales were videotaped while feeding at the surface, mid-water, and bottom. The ingestion sequence includes a preparatory phase with partial gape followed by jaw opening and rapid hyoid depression to suck in prey at a mean distance of 14 cm (duration 90 msec), although prey were taken from much greater distances. Depression and retraction of the large, piston-like tongue generate negative intraoral pressures for prey capture and ingestion. Food was normally ingested without grasping by teeth yet was manipulated with lingual, hyoid, and mandibular movement for realignment; suction was then used to transport prey into the oropharynx. Whales frequently rolled or inverted before taking prey, presumably to avoid grasping and repositioning. Prey were sucked off the bottom or sides of the pool without direct contact; lateral suction was used to ingest items from the sides of the mouth.     

Microbiological Sterol Conversions: Utilization of Selected Mutants

Microbiological conversion of drugs and natural products, including sterols and steroids, is an important component of the commercial preparation of these agents. We have developed methodology which allows for the production and selection of mutant organisms capable of specific desirable transformations. This methodology is based upon mutation of wild-type strains which are capable of completely degrading certain sterols and selection of the mutants blocked at the desired conversion. This procedure should be equally useful for many if not all drug classes.     

Multi‐jawed chaetognaths from the Chengjiang Lagerstätte (Cambrian,Series 2, Stage 3) of Yunnan,China

Chaetognaths (arrow‐worms) are enigmatic in terms of their phylogenetic position, while the existence of Protosagitta spinosa from the Chengjiang Lagerstätte suggests minimal change in their unique bodyplan since at least the early Cambrian. Apart from rare (and sometimes controversial) soft‐bodied remains, the fossil record of chaetognaths is otherwise almost entirely dependent on early Palaeozoic phosphatic microfossils, some of which are placed amongst so‐called protoconodonts. Fused spine clusters are strikingly similar to the cephalic grasping apparatus of extant forms and are assumed to have had a comparable configuration. Here we report a new chaetognath, Ankalodous sericus gen. et sp. nov., coeval with Protosagitta but with a complex feeding apparatus consisting of multiple bundles of recurved spines whose principal function appears to have been grasping. Like all other chaetognaths a predatory mode of life is likely, but its position relative to the sediment–water interface is less certain. Reduction of the feeding apparatus, from the multi‐jawed arrangement of A. sericus to the grasping spines and associated smaller teeth seen in other chaetognaths, was probably a subsequent development and conceivably was linked with a shift to a pelagic mode of life. We also report a new specimen of Protosagitta. This confirms earlier observations but it possesses hitherto unrecognized features, including a cephalic tentacle and fin rays.     

Orang-like manual adaptations in the fossil hominoid Hispanopithecus laietanus: first steps towards great ape suspensory behaviours

Morphological and biometrical analyses of the partial hand IPS18800 of the fossil great ape Hispanopithecus laietanus (=Dryopithecus laietanus), from the Late Miocene (about 9.5Ma) of Can Llobateres (Catalonia, Spain), reveal many similarities with extant orang-utans (Pongo). These similarities are interpreted as adaptations to below-branch suspensory behaviours, including arm-swinging and clambering/postural feeding on slender arboreal supports, due to an orang-like double-locking mechanism. This is confirmed by the long and highly curved phalanges of Hispanopithecus. The short and stout metacarpals with dorsally constricted heads, together with the dorsally extended articular facets on proximal phalanges, indicate the persistence of significant degrees of palmigrady. A powerful grasping capability is indicated by the great development of basal phalangeal tubercles, the marked insertions for the flexors on phalangeal shafts and the large pits for the collateral ligaments. The morphology of the Hispanopithecus long bones of the hand indicates a unique positional repertoire, combining orthogrady with suspensory behaviours and palmigrade quadrupedalism. The retention of powerful grasping and palmigrady suggests that the last common ancestor of hominids might have been more primitive than what can be inferred on the basis of extant taxa, suggesting that pronograde behaviours are compatible with an orthograde bodyplan suitable for climbing and suspension.     

Computing the reversal distance between genomes in the presence of multi-gene families via binary integer programming

Hannenhalli and Pevzner developed the first polynomial-time algorithm for the combinatorial problem of sorting signed genomic data. Their algorithm determines the minimum number of reversals required for rearranging a genome to another -but only in the absence of gene duplicates. However, duplicates often account for 40% of a genome. In this paper, we show how to extend Hannenhalli and Pevzner's approach to deal with genomes with multi-gene families. We propose a new heuristic algorithm to compute the nearest reversal distance between two genomes with multi-gene families via binary integer programming. The experimental results on both synthetic and real biological data demonstrate that the proposed algorithm is able to find the reversal distance with high accuracy.     

Complexities and algorithms for glycan sequencing using tandem mass spectrometry

Determining glycan structures is vital to comprehend cell-matrix, cell-cell, and even intracellular biological events. Glycan sequencing, which determines the primary structure of a glycan using tandem mass spectrometry (MS/MS), remains one of the most important tasks in proteomics. Analogous to peptide de novo sequencing, glycan de novo sequencing determines the structure without the aid of a known glycan database. We show in this paper that glycan de novo sequencing is NP-hard. We then provide a heuristic algorithm and develop a software program to solve the problem in practical cases. Experiments on real MS/MS data of glycopeptides demonstrate that our heuristic algorithm gives satisfactory results on practical data.     

Development of an allele-mining set in rice using a heuristic algorithm and SSR genotype data with least redundancy for the post-genomic era

The allelic diversity of a collection of 4046 rice accessions was assessed using 15 neutral SSR markers distributed throughout the genome. A total of 482 alleles were detected; the average allelic richness was 32.1 alleles per locus. Using a heuristic approach, an allele-mining set was successfully developed on the basis of SSR marker data. 162 accessions of the allele-mining set, accounting for about 4.0% of the entire collection, captured all of the alleles (482) retained in the entire collection, which showed 100% coverage of alleles with minimum redundancy. As a result of validation of this heuristic approach using another 14 SSR markers associated with starch, 70% of the total alleles and 83% of the restricted alleles (allele frequency > 0.05%) were captured in this allele-mining set. The results showed that the heuristic approach meets the condition as an allele-mining set even when applied to another specific set of markers related to starch synthesis in the same entire and allele-mining set. The newly developed methodology for developing allele-mining sets can be used in other crop species. By retaining all alleles of the entire collection, this allele-mining set will be useful for future studies on introducing unused useful alleles into elite rice varieties by breeders in the post-genomic era.     

An Efficient Heuristic Approach to Recognize the Infeasibility of a Loading Problem

The success of hierarchical production planning approaches for flexible manufacturing systems lies in the consistency of decision outcomes at various decision levels. For instance, the loading problem, which is solved at a lower level, may not yield a feasible loading solution to a set of part types selected at a higher level. This paper attemps to address the issue of recognizing the infeasibility of a loading solution. We present a modified loading model that includes a penalty for each operation not assigned to any machine. We develop a Lagrangian-based heuristic procedure and provide a sufficient condition on the quality of heuristic solutions that, if satisfied, will enable us to use the heuristic solutions to recognize the infeasibility of a loading problem. The proposed model and the dual-based heuristic can be effectively incorporated in an FMS hierarchical production planning approach that finds a good loading solution by iteratively comparing different part grouping scenarios.