2,019 research outputs found
Laser-Excited Elastic Guided Waves Reveal the Complex Mechanics of Nanoporous Silicon
Nanoporosity in silicon leads to completely new functionalities of this
mainstream semiconductor. A difficult to assess mechanics has however
significantly limited its application in fields ranging from nanofluidics and
biosensorics to drug delivery, energy storage and photonics. Here, we present a
study on laser-excited elastic guided waves detected contactless and
non-destructively in dry and liquid-infused single-crystalline porous silicon.
These experiments reveal that the self-organised formation of 100 billions of
parallel nanopores per square centimetre cross section results in a nearly
isotropic elasticity perpendicular to the pore axes and an 80% effective
stiffness reduction, altogether leading to significant deviations from the
cubic anisotropy observed in bulk silicon. Our thorough assessment of the
wafer-scale mechanics of nanoporous silicon provides the base for predictive
applications in robust on-chip devices and evidences that recent breakthroughs
in laser ultrasonics open up entirely new frontiers for in-situ,
non-destructive mechanical characterisation of dry and liquid-functionalised
porous materials.Comment: 12 pages, 8 figures, Supplementary information available as ancillary
file, in pres
Standard Specifications for Highway and Bridge Construction, 2012
When referenced, the 2012 edition of the Iowa Department of Transportationâs (Iowa DOT)
Standard Specifications for Highway and Bridge Construction shall be used for contract work
awarded by the Iowa DOT. They may also be incorporated by reference in other contract work
on secondary, urban, local systems, or other contract work in which the Iowa DOT has an
interest. As modified by the General Supplemental Specifications, these Standard
Specifications represent the minimum requirements and may be modified by Supplemental Specifications, Developmental Specifications, and Special Provisions on specific
contracts. These Standard Specifications have been written so the Contractorâs responsibilities are indicated by plain language using the Imperative Mood and
Active Voice form. Sentences are of the form: Construct isolation joints at all points
where driveways meet other walks, curbs, or fixtures in the surface.
Ensure finished members are true to detailed dimensions and free from
twists, bends, open joints, or other defects resulting from faulty fabrication
or defective work. Personnel preparing the JMF shall be Iowa DOT certified in bituminous mix design. The Contracting Authorityâs responsibilities are (with some exceptions) indicated by the use of the modal verb âwillâ. Sentences are of the form: The Engineer will obtain and test density samples for each lot according to Materials I.M. 204. Payment will be the contract unit price for Fabric Reinforcement per square yard (square meter).
These standard specifications contain dual units of measure: the United States Standard measure (English units) and the International System of Units (SI or âmetricâ units). The English units are expressed first then followed by the metric units in parentheses. The measurements expressed in the two systems are not necessarily equal. In some cases the measurements in metric units is a âhardâ conversion of the English measurement; i.e. the metric unit has been approximated with a rounded, rationalized metric measurement that is easy to work with and remember. The proposal form will identify whether the work was designed and shall be constructed in English or metric units
Small Atlas of Johannesburg
After two decades of significant change, Johannesburg has been expanding and undergoing deep restructuring. Today, the city is going through an unprecedented development phase, initiated by new territorial dynamics resulting from urban policies, resident practices and market trends. While Johannesburg aims to become a âWorld Class African Cityâ, as a part of managing its growth it is essential to offer an accurate image of its strengths and weaknesses. The issue of urban resilience has become central to the discourse on cities and calls for light to be shed on the evolutions that have shaped and continue to shape the city of Johannesburg. In this light, we focus on major urban phenomena including: The spatial evolution of the city where densification is not always synonymous with urbanity; Increasing spatial differentiations according to population and housing; Increasingly fragmented and extensive spatial structuring. In this publication, special attention has been given to the compilation of former and recent data. These data, depending on objective geographic elements, show how âvarious citiesâ exist within the city. Overcoming the limitations of the data was the main difficulty. Urban evolutions are rapid, but existing data are difficult to access and are often out of date or localised, as part of unsuitable divisions. Various comments have been written to shed light on the maps and facilitate their reading. The objective of this work is to create a coherent set of maps so as to offer a homogeneous vision of the city and urbanisation processes underlining it
Overcoming the Challenges for Multichip Integration: A Wireless Interconnect Approach
The physical limitations in the area, power density, and yield restrict the scalability of the single-chip multicore system to a relatively small number of cores. Instead of having a large chip, aggregating multiple smaller chips can overcome these physical limitations. Combining multiple dies can be done either by stacking vertically or by placing side-by-side on the same substrate within a single package. However, in order to be widely accepted, both multichip integration techniques need to overcome significant challenges.
In the horizontally integrated multichip system, traditional inter-chip I/O does not scale well with technology scaling due to limitations of the pitch. Moreover, to transfer data between cores or memory components from one chip to another, state-of-the-art inter-chip communication over wireline channels require data signals to travel from internal nets to the peripheral I/O ports and then get routed over the inter-chip channels to the I/O port of the destination chip. Following this, the data is finally routed from the I/O to internal nets of the target chip over a wireline interconnect fabric. This multi-hop communication increases energy consumption while decreasing data bandwidth in a multichip system. On the other hand, in vertically integrated multichip system, the high power density resulting from the placement of computational components on top of each other aggravates the thermal issues of the chip leading to degraded performance and reduced reliability. Liquid cooling through microfluidic channels can provide cooling capabilities required for effective management of chip temperatures in vertical integration. However, to reduce the mechanical stresses and at the same time, to ensure temperature uniformity and adequate cooling competencies, the height and width of the microchannels need to be increased. This limits the area available to route Through-Silicon-Vias (TSVs) across the cooling layers and make the co-existence and co-design of TSVs and microchannels extreamly challenging.
Research in recent years has demonstrated that on-chip and off-chip wireless interconnects are capable of establishing radio communications within as well as between multiple chips. The primary goal of this dissertation is to propose design principals targeting both horizontally and vertically integrated multichip system to provide high bandwidth, low latency, and energy efficient data communication by utilizing mm-wave wireless interconnects. The proposed solution has two parts: the first part proposes design methodology of a seamless hybrid wired and wireless interconnection network for the horizontally integrated multichip system to enable direct chip-to-chip communication between internal cores. Whereas the second part proposes a Wireless Network-on-Chip (WiNoC) architecture for the vertically integrated multichip system to realize data communication across interlayer microfluidic coolers eliminating the need to place and route signal TSVs through the cooling layers. The integration of wireless interconnect will significantly reduce the complexity of the co-design of TSV based interconnects and microchannel based interlayer cooling. Finally, this dissertation presents a combined trade-off evaluation of such wireless integration system in both horizontal and vertical sense and provides future directions for the design of the multichip system
Standard Specifications for Road and Bridge Construction, January 1, 2015
https://digitalcommons.memphis.edu/govpubs-tn-dept-transportation-standard-specifications/1006/thumbnail.jp
Standard Specifications for Road and Bridge Construction, January 1, 2021
https://digitalcommons.memphis.edu/govpubs-tn-dept-transportation-standard-specifications/1000/thumbnail.jp
Volume 11, issue 3
The mission of CJS is to contribute to the effective continuing medical education of Canadian surgical specialists, using innovative techniques when feasible, and to provide surgeons with an effective vehicle for the dissemination of observations in the areas of clinical and basic science research.
Visit the journal website at http://canjsurg.ca/ for more.https://ir.lib.uwo.ca/cjs/1090/thumbnail.jp
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