Design of Single-Input-Single-Output Compliant Mechanisms for Practical Applications Using Selection Maps

We present an interactive map-based technique for designing single-input-single-output compliant mechanisms that meet the requirements of practical applications. Our map juxtaposes user-specifications with the attributes of real compliant mechanisms stored in a database so that not only the practical feasibility of the specifications can be discerned quickly but also modifications can be done interactively to the existing compliant mechanisms. The practical utility of the method presented here exceeds that of shape and size optimizations because it accounts for manufacturing considerations, stress limits, and material selection. The premise for the method is the spring-leverage (SL) model, which characterizes the kinematic and elastostatic behavior of compliant mechanisms with only three SL constants. The user-specifications are met interactively using the beam-based 2D models of compliant mechanisms by changing their attributes such as: (i) overall size in two planar orthogonal directions, separately and together, (ii) uniform resizing of the in-plane widths of all the beam elements, (iii) uniform resizing of the out-of-plane thick-nesses of the beam elements, and (iv) the material. We present a design software program with a graphical user interface for interactive design. A case-study that describes the design procedure in detail is also presented while additional case-studies are posted on a website. DOI:10.1115/1.4001877].

Practical Proposals for Specifying k-Nearest Neighbours Weights Matrices

In this article we introduce and evaluate testing procedures for specifying the number k of nearest neighbours in the weights matrix of spatial econometric models. The spatial J-test is used for specification search. Two testing procedures are suggested: an increasing neighbours testing procedure and a decreasing neighbours testing procedure. Simulations show that the increasing neighbours testing procedures can be used in large samples to determine k. The decreasing neighbours testing procedure is found to have low power, and is not recommended for use in practice. An empirical example involving house price data is provided to show how to use the testing procedures with real data.

Optimal Receive Antenna Selection in Time-Varying Fading Channels with Practical Training Constraints

Hardware constraints, which motivate receive antenna selection, also require that various antenna elements at the receiver be sounded sequentially to obtain estimates required for selecting the `best' antenna and for coherently demodulating data thereafter. Consequently, the channel state information at different antennas is outdated by different amounts and corrupted by noise. We show that, for this reason, simply selecting the antenna with the highest estimated channel gain is not optimum. Rather, a preferable strategy is to linearly weight the channel estimates of different antennas differently, depending on the training scheme. We derive closed-form expressions for the symbol error probability (SEP) of AS for MPSK and MQAM in time-varying Rayleigh fading channels for arbitrary selection weights, and validate them with simulations. We then characterize explicitly the optimal selection weights that minimize the SEP. We also consider packet reception, in which multiple symbols of a packet are received by the same antenna. New suboptimal, but computationally efficient weighted selection schemes are proposed for reducing the packet error rate. The benefits of weighted selection are also demonstrated using a practical channel code used in third generation cellular systems. Our results show that optimal weighted selection yields a significant performance gain over conventional unweighted selection.

A novel supersecondary structure in globular proteins comprising the collagen-like helix and ?-turn

A structure consisting of the polyproline-II or collagen-like helix immediately succeeded by a ?-turn is seen in several synthetic peptides and has been suggested to be the conformational requirement for proline hydroxylation in nascent procollagen. Using a simple algorithm for detecting secondary structures, we have analysed crystal structure data on 40 globular proteins and have found eight examples of the collagen-helix + ?-turn supersecondary structure in 15 proteins that contain the collagen-like helical segments.

b-Turn conformations in crystal structures of model peptides containing a,a-di-n-propylglycine (Dpg) and a,a-di-n-butyl-glycine (Dbg).

The crystal state conformations of three peptides containing the a,a-dialkylated residues, a,adi n-propylglycine (Dpg) and a,@-di-n-butylglycine (Dbg), have been established by x-ray diffraction. Boc-Ala-Dpg-Ala-OMe ( I ) and Boc-Ala-Dbg-Ala-OMe (III) adopt distorted type II @-turn conformations with Ala ( I ) and Dpg/Dbg (2) as the corner residues. In both peptides the conformational angles at the Dxg residue (I: 4 = 66.23 J/ = 19.3'; III: 4 = 66S0, J. = 21 .la)deviate appreciablyfrom ideal values for the i + 2 residue in a type II @-turn. In both peptides the observed(N. 0) distances between the Boc CO andAla(3) NHgroups are far too long (I:3.44 k; III: 3.63 k) for an intramolecular 4 + 1 hydrogen bond. Boc-Ala-Dpg-Ala-NHMe (II)crystallizes with two independent molecules in the asymmetric unit. Both molecules IIA and IIB adopt consecutive @-turn (type III-III in IIA and type III-I in IIB) or incipient 3,,,-helical structures, stabilized by two intramolecular 4 --t I hydrogen bonds. In all four molecules the bond angle N-C"-C' ( T ) at the Dxg residues are 2 1109 The observation of conformational angles in the helical region of 4,J/ space at these residues is consistent with theoretical predictions

A nonhelical, multiple β-turn conformation in a glycine-rich heptapeptide fragment of trichogin A IV containing a single central α-aminoisobutyric acid residue

The conformational properties of the protected seven-residue C-terminal fragment the lipopeptaibol antibiotic Trichogin A IV (Boc-Gly-Gly-Leu-Aib-Gly-Ile-Leu-OMe) has been examined in CDCl3 and (CD3)2SO by 1H-nmr. Evidence for a multiple β-turn conformation [type I′ at Gly(1)-Gly(2), type II at Leu(3)-Aib(4), and a type I′ at Aib(4)-Gly(5)] suggests that Leu(3) has preferred an extended or semiextended conformation over a helical conformation in CDCl3. This structure is thus in contrast to earlier observations of seven-residue peptides containing a single central Aib preferring helical conformations in both solution and crystalline slates. A structural transition to a frayed right-handed helix is absented in (CD3)2SO. These results suggest that nonhelical conformations may be important in Gly-rich peptides containing Aib. Further, the presence of amino acids with contradictory influences on backbone conformational freedom can lead to well-defined conformational transitions even in small peptides

Vacuum ultraviolet circular dichroism spectrum of β-turn in solution

The vacuum ultraviolet circular dichroism spectrum of an isolated 4 → 1 hydrogen bonded β-turn is reported. The observed spectrum of N-acetyl-Pro-Gly-Leu-OH at − 40°C in trifluoroethanol is in good agreement with the theoretically calculated CD spectrum of the β-turn conformation. This spectrum, particularly the presence of a strong negative band around 180 nm and a large ratio [θ]201/[θ]225, can be taken as a characteristic feature of the isolated β-turn conformation. These CD spectral features can thus be used to distinguish the β-turn conformation from the β-structure in solution.

Changing Paradigms in Biblical Criticism : 2 Kings 22:1 23:30 in the Flux of Discourses

The subject and methodology of biblical scholarship has expanded immense-ly during the last few decades. The traditional text-, literary-, source- and form-critical approaches, labeled historical-critical scholarship , have faced the challenge of social sciences. Various new literary, synchronic readings, sometimes characterized with the vague term postmodernism, have in turn challenged historicalcritical, and social-scientific approaches. Widened limits and diverging methodologies have caused a sense of crisis in biblical criticism. This metatheoretical thesis attempts to bridge the gap between philosophical discussion about the basis of biblical criticism and practical academic biblical scholarship. The study attempts to trace those epistemological changes that have produced the wealth of methods and results within biblical criticism. The account of the cult reform of King Josiah of Judah as reported in 2 Kings 22:1 23:30 serves as the case study because of its importance for critical study of the Hebrew Bible. Various scholarly approaches embracing 2 Kings 22:1 23:30 are experimentally arranged around four methodological positions: text, author, reader, and context. The heuristic model is a tentative application of Oliver Jahraus s model of four paradigms in literary theory. The study argues for six theses: 1) Our knowledge of the world is con-structed, fallible and theory-laden. 2) Methodological plurality is the neces-sary result of changes in epistemology and culture in general. 3) Oliver Jahraus s four methodological positions in regard to literature are also an applicable model within biblical criticism to comprehend the methodological plurality embracing the study of the Hebrew Bible. 4) Underlying the methodological discourse embracing biblical criticism is the epistemological ten-sion between the natural sciences and the humanities. 5) Biblical scholars should reconsider and analyze in detail concepts such as author and editor to overcome the dichotomy between the Göttingen and Cross schools. 6) To say something about the historicity of 2 Kings 22:1 23:30 one must bring together disparate elements from various disciplines and, finally, admit that though it may be possible to draw some permanent results, our conclusions often remain provisional.

Proofs, Paradoxes, and Probabilities : The Logical Turn of Philosophy in Finland

This monograph describes the emergence of independent research on logic in Finland. The emphasis is placed on three well-known students of Eino Kaila: Georg Henrik von Wright (1916-2003), Erik Stenius (1911-1990), and Oiva Ketonen (1913-2000), and their research between the early 1930s and the early 1950s. The early academic work of these scholars laid the foundations for today's strong tradition in logic in Finland and also became internationally recognized. However, due attention has not been given to these works later, nor have they been comprehensively presented together. Each chapter of the book focuses on the life and work of one of Kaila's aforementioned students, with a fourth chapter discussing works on logic by authors who would later become known within other disciplines. Through an extensive use of correspondence and other archived material, some insight has been gained into the persons behind the academic personae. Unique and unpublished biographical material has been available for this task. The chapter on Oiva Ketonen focuses primarily on his work on what is today known as proof theory, especially on his proof theoretical system with invertible rules that permits a terminating root-first proof search. The independency of the parallel postulate is proved as an example of the strength of root-first proof search. Ketonen was to our knowledge Gerhard Gentzen's (the 'father' of proof theory) only student. Correspondence and a hitherto unavailable autobiographic manuscript, in addition to an unpublished article on the relationship between logic and epistemology, is presented. The chapter on Erik Stenius discusses his work on paradoxes and set theory, more specifically on how a rigid theory of definitions is employed to avoid these paradoxes. A presentation by Paul Bernays on Stenius' attempt at a proof of the consistency of arithmetic is reconstructed based on Bernays' lecture notes. Stenius correspondence with Paul Bernays, Evert Beth, and Georg Kreisel is discussed. The chapter on Georg Henrik von Wright presents his early work on probability and epistemology, along with his later work on modal logic that made him internationally famous. Correspondence from various archives (especially with Kaila and Charlie Dunbar Broad) further discusses his academic achievements and his experiences during the challenging circumstances of the 1940s.

Practical constant-accuracy linear weir

This paper is concerned with the modifications of the Extended Bellmouth Weir (EBM weir) earlier designed by Keshava Murthy. It is shown that by providing inclined sides (equivalent to providing an inward-trapezoidal weir) over a sector of a circle of radius R, separated by a distance 2t, and depth d, the measurable range of EBM can be considerably enhanced (over 375%). Simultaneously, the other parameters of the weir are optimized such that the reference plane of the weir coincides with its crest making it a constant-accuracy linear weir. Discharge through the aforementioned weir is proportional to the depths of flow measured above the crest of the weir for all heads in the range of 0.5R less-than-or-equal-to h less-than-or-equal-to 7.9R, within a maximum deviation of +/-1% from the theoretical discharge. Experiments with two typical weirs show excellent agreement with the theory by giving a constant-average coefficient of discharge of 0.619

Covariant differentials lead to the design of a novel self-tuning power system stabilizer

Application of differential geometry to study the dynamics of electrical machines by Gabriel Kron evoked only theoretical interest among the power system engineers and was considered hardly suitable for any practical use. Extension of Kron's work led to a physical understanding of the processes governing the small oscillation instability in power system. This in turn has made it possible to design a self-tuning Power System Stabilizer to contain the oscillatory instability over arm extended range of system and operating conditions. This paper briefly recounts the history of this development and touches upon the essential design features of the stabilizer. It presents some results from simulation studies, laboratory experiments and recently conducted field trials at actual plants-all of which help to establish the efficacy of the proposed stabilizer and corroborate the theoretical findings.