Packaging Constraints Research Articles

Numerical Investigation on Airflow Distribution of Automotive Radiator

In automobiles due to styling and packaging constraints there are several blockages in the upstream and downstream direction of radiator, which interrupts the uniform airflow distribution. However, airflow distribution on the radiator face plays a key role in improving its effectiveness. The objective of this work is to analyze the impact of airflow distribution and uniformity index with different types of blockages ahead of the radiator using Computational Fluid Dynamics (CFD) tool. Four different geometry blockages are considered for this study and analyzed further to arrive at the better Uniformity index. The different blockage geometries considered are horizontal, vertical, side to side and side to center. It is observed that side to side geometry blockage gives poor velocity distribution compared to others. Also CFD model is validated with experimental result and good agreement has been observed between predicted and measured velocity pattern over the radiator. In addition to this, a statistical study is conducted to analyze the influence of various parameters like fan speed and ram air speed along with types of blockage on the uniformity index. It is observed that, type of blockage have the significant impact on the uniformity index. The interpretations of this work can serve as a design guideline for the thermal system and styling engineers of automotive domain.

Diesel engine performance improvement with suitable low cost technologies for tractor applications

Off-road engines for tractor applications are developed with limited space due to packaging constraints and low cost targets. Hence major challenges faced by several off-road engine manufactures are to achieve higher power density and to comply emission legislation with low cost modifications. Henceforth in this work a cost-effective research approach is investigated for conversion of naturally aspirated (NA) engine to turbocharged intercooled for off-road diesel engines performance improvement. Further, reducing the charge air temperature into the engine by using water spray cooled intercooler strategy minimised the combustion temperature, consequently power and torque increased. To reduce the exhaust emission such as oxides of nitrogen (NOx), strategies such as cooled exhaust gas recirculation (EGR) are computationally optimised. This analysis is executed for selection of the EGR cooler tube to achieve better exhaust gas cooling effectiveness. In addition to the NOx reduction strategy, substrate volume for lean NOx trap is also optimised to investigate its effectiveness in this research work.

High-Speed Photodiodes

To meet the challenge of broad bandwidth and high-responsivity numerous photodetector approaches have been investigated. Normal-incidence photodiodes have the advantages of relatively simple structures, high responsivity, and relaxed packaging constraints for bandwidths of a few gigahertz. Achieving acceptable responsivity at higher speed necessitates the use of waveguide structures. The emergence of Si photonics has also relied on developing suitable waveguide photodiodes. This paper reviews the technologies employed for high-speed photodiodes and state-of-the-art performance.

Structural constraints in the packaging of bluetongue virus genomic segments.

The mechanism used by bluetongue virus (BTV) to ensure the sorting and packaging of its 10 genomic segments is still poorly understood. In this study, we investigated the packaging constraints for two BTV genomic segments from two different serotypes. Segment 4 (S4) of BTV serotype 9 was mutated sequentially and packaging of mutant ssRNAs was investigated by two newly developed RNA packaging assay systems, one in vivo and the other in vitro. Modelling of the mutated ssRNA followed by biochemical data analysis suggested that a conformational motif formed by interaction of the 5′ and 3′ ends of the molecule was necessary and sufficient for packaging. A similar structural signal was also identified in S8 of BTV serotype 1. Furthermore, the same conformational analysis of secondary structures for positive-sense ssRNAs was used to generate a chimeric segment that maintained the putative packaging motif but contained unrelated internal sequences. This chimeric segment was packaged successfully, confirming that the motif identified directs the correct packaging of the segment.

Numerical analysis of thermo-mechanical and mobility effects for 28 nm node and beyond: Comparison and design consequences over bumping technologies

Thanks to finite elements simulation and dedicated post-processing routines, this paper explores stress induced mobility changes over three major bumping processes. A numerical comparative analysis over the assembly generations is carried out. In order to do so, models are built for solder flip chip, copper pillar flip chip and micro-copper pillar bumping. Design recommendations for MOSFET placement to include in conception tools are provided, which allow to ensure adherence to product specifications while technologies advance.It is demonstrated that stress effects on mobility are widely dependent on the integration flow, and transistor placements must be considered accordingly. Despite the fact that, qualitatively speaking, the generated stress states are quite similar for whole bumping schemes, the quantitative variations of each stress components in combination with the piezo resistive coefficients of silicon lead to distinct effective mobility variations. As a consequence, design rules and keep out zones can be optimized specifically for each assembly technology. More precisely, it is advised to avoid nMOS placement directly below the bump in flip chip devices, for which the mobility can be degraded by almost 5%. In these cases keep out zones must be considered. Reversely, in the case of 3DICs, the performances of nMOS are improved by more than 2% in that region, which means that no restriction is required and silicon area can hence be saved. As for the p type carriers, variability is sensitive to channel orientation rather than their location with respect to the bump: more precisely, the transport direction must be azimuthally oriented, and radially oriented pMOS are proscribed. Maximum variations of about ±5% are found for the copper pillar flip chip configuration. Thanks to a comprehensive analysis, FEoL designers will be able to integrate BEoL and packaging constraints during the conception phases of advanced semiconductor products.

Development of a light vehicle diesel aftertreatment system with DOC DPF and urea SCR

Meeting stringent emission regulations is a challenge to light vehicle diesel engines because of complexities of aftertreatment system, packaging constraints, and emission regulations. This article intends to introduce development philosophy from developing a light vehicle aftertreatment system that includes diesel oxidisation catalyst (DOC), catalytic diesel particulate filter (CDPF), urea injector and urea selective catalytic reduction (SCR). The development focus was on overall component planning to meet system emission targets at the early stage, system geometrical optimisations to meet pressure target at the intermediate stage, and design improvements of urea SCR module at the final stage. Both tests and modelling were employed seamlessly to reach decisions on major design directions. Significant efforts were spent on SCR mixing optimisation. Multiple mixer concepts were explored; the final developed SCR system was tested and able to meet all performance objectives. The roles of computational fluid dynamics (CFD) spray modelling and emission tests are discussed.

Heterogeneous Integration of Photonic Integrated Circuits Using 3D Assembly Techniques: Silicon Technology and Packaging

The large internet companies' investments indicate an ongoing increase of data-based business volume through the next decades with the rise of the internet of things and the continuous growth of communication and data facilities. The two-figure yearly growth rate of exchanged data volume within data centers is challenging the actual short distance communication paradigms. With datacenter architectures getting larger and “flatter”, the availability of high bandwidth, low power and low cost optical links ranging from less than 1 meter to 1 kilometer is a key issue. It is therefore expected that today's 10 Gb/s transceiver data rate soon increase to 28Gb/s, 40 Gb/s and beyond. For such a channel bandwidth, the copper-based wires are no longer suitable in terms of cost, power and bandwidth density. Optical interconnects are expected to replace copper for short distances below 500 m and down to 1 m within servers and between servers of the same data center. They exhibit much higher scalability and flexibility in terms of bandwidth, reach and lower energy consumption down to 1 pJ/b and below. The integration of optical transceivers close to the computational logic is therefore becoming more and more attractive. The enabling technology for optical interconnect is silicon photonics which is maturing and leveraging the well-established knowledge coming from silicon technology. We today have a complete set of silicon photonics technology modules that cover passive components including multiplexers/demultiplexers, coupling functions, photodetectors, modulators and integrated laser sources. Given the constraints coming from the supply chain, we consider a heterogeneous integration of the photonics (PIC) and the electrical integrated circuits (EIC) within a single package, differentiating from a co-integration of both of them on a single die demonstrated in the past, which is not a viable nor scalable option from the economical point of view. Thereby we leverage our expertise in the 3D integration field, and we use a full set of mature technology modules including through-silicon vias (TSV), wafer thinning and micro-bumping. These modules have only been used in the past within electrical circuits, but their implantation in photonics chips has no showstoppers. The 3D integration enables a stacking of the electrical drivers in the EIC die on top of the photodiodes and modulators in the PIC die. The small micro-bump size reduces the parasitic capacitances and enables an optimized electro-optical co-design. The TSV enable the connection of the stack with the rest of the package and to the second-level interconnect with low inductive losses, thus boosting the system performance. The advanced 3D packaging technique also enables the alignment and attachment of the optical fibers using silicon micro-ferrules. Today's active alignment techniques for optical coupling are time-consuming and expensive, and not compatible with usual micro-electronics techniques. The ongoing development of silicon micro-ferrules with mechanical micro-bumps enables a compatible assembly of the optical plugs with the remaining system and a quick assembly process with standard pick-and-place equipment. The paper will introduce today's system demand in the data base market and its translation into technology requirements. It will then survey our silicon photonics technology modules and actual demonstrations. We will then introduce the packaging constraints and the impact of 3D integration on the system assembly. Finally, we will present our advances in terms of packaging of optical micro-connectors.

The effect of half-shaft torsion dynamics on the performance of a traction control system for electric vehicles

This article deals with the dynamic properties of individual wheel electric powertrains for fully electric vehicles, characterised by an in-board location of the motor and transmission, connected to the wheel through half-shafts. Such a layout is applicable to vehicles characterised by significant power and torque requirements where the adoption of in-wheel electric powertrains is not feasible because of packaging constraints. However, the dynamic performance of in-board electric powertrains, especially if adopted for anti-lock braking or traction control, can be affected by the torsional dynamics of the half-shafts. This article presents the dynamic analysis of in-board electric powertrains in both the time domain and the frequency domain. A feedback control system, incorporating state estimation through an extended Kalman filter, is implemented in order to compensate for the effect of the half-shaft dynamics. The effectiveness of the new controller is demonstrated through analysis of the improvement in the performance of the traction control system.

Wet Sump Design for a FSAE Racing Car

The problem statement consisted of designing a Wet Sump Lubrication system for Formula Manipal, Manipal Institute of Technology's FSAE racing team. The team uses a 2003 specification Honda CBR 600RR motorcycle engine to power the rear wheels by means of a chain drive and a limited slip differential. Packaging and performance constraints meant that the stock oil pan could not be retained. It was thus proposed to design and manufacture a custom wet sump oil pan and validate it by testing. The goal was to build a lubrication system which worked flawlessly in a racing environment including acceleration, braking and cornering. This was realized by innovatively placing baffles and a windage tray in the oil pan. At the same time, it was important to reduce the height of the oil pan so as to allow the engine to be mounted lower in the chassis, facilitate better packaging and improve the dynamic performance of the car.

Self-Contained, Hand-Portable, and Repetitive Ultrawideband Radiation Source

This paper presents the design and experimental results of a hand-portable, self-contained, and repetitive radiation source of high-power ultrawideband (UWB) pulses. This source consists of a deployed UWB antenna driven by a high-pulsed power (HPP) generator and powered by a self-contained 50-kV rapid charger at repetition rates up to 100 Hz. By changing the HPP generator, two different electric wave shapes with two different frequency spectra can be generated. Each HPP generator is based on the use of a repetitive Marx generator. On the one hand, a 200-kV/1.4-J Marx generator is associated with a coaxial pulse-forming stage consisting of two highly pressurized spark gap switches and a Blumlein line, which produces bipolar pulses. Its main characteristics are an output voltage of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$+$</tex></formula> 100 kV/ <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 100 kV and a pulsewidth of 1.5 ns. On the other hand, we have developed a second eight-stage Marx generator, where the pulse-forming stage is the last stage of the structure. It delivers pulses in the 150-kV/1-J range, with a fall time of 300 ps and an 850-ps pulse duration. Electrical signals are radiated by a deployed Valentine antenna. It is a new traveling wave antenna that is designed to radiate high-voltage repetitive pulses with the challenge of high gain and low dispersion in an extremely restricted volume. The design of a rapid charging power supply is also presented, meeting stringent package constraints while still enabling high repetition rates. It has already demonstrated its capability of charging, from a dc power battery, a 5-nF capacitance up to 50 kV in 5 ms at a 100-Hz repetition rate for some bursts of thousand pulses. The autonomy is more than 35 000 shots (depending on the number of battery packs inside). Electric field measurements were performed on the whole package to determine the figure of merit (the maximum value of far-field peak electric field strength multiplied by the distance) of the UWB source in each configuration (bipolar and monopolar sets). The figure of merit measured is 200 kV for both.

Modeling Indivisible Demand

Disaggregate demand in the marketplace exists on a grid determined by the package sizes offered by manufacturers and retailers. While consumers may want to purchase a continuous-valued amount of a product, realized purchases are constrained by available packages. This constraint might not be problematic for high-volume demand, but it is potentially troubling when demand is small. Despite the prevalence of packaging constraints on choice, economic models of choice have been slow to deal with their effects on parameter estimates and policy implications. In this paper we propose a general framework for dealing with indivisible demand in economic models of choice, and show how to estimate model parameters using Bayesian methods. Analyses of simulated data and a scanner-panel dataset of yogurt purchases indicate that ignoring packaging constraints can severely bias parameter estimates and measures of model fit, which results in the inaccurate measures of metrics such as price elasticity and compensating value. We also show that 9.52% of non-purchase in the data reflects the restriction of indivisibility, not the lack of preference.

Modeling Indivisible Demand

Disaggregate demand in the marketplace exists on a grid determined by the package sizes offered by manufacturers and retailers. Although consumers may want to purchase a continuous-valued amount of a product, realized purchases are constrained by available packages. This constraint might not be problematic for high-volume demand, but it is potentially troubling when demand is small. Despite the prevalence of packaging constraints on choice, economic models of choice have been slow to deal with their effects on parameter estimates and policy implications. In this paper we propose a general framework for dealing with indivisible demand in economic models of choice, and we show how to estimate model parameters using Bayesian methods. Analyses of simulated data and a scanner-panel data set of yogurt purchases indicate that ignoring packaging constraints can bias parameter estimates and measures of model fit, which results in the inaccurate measures of metrics such as price elasticity and compensating value. We also show that a portion of nonpurchase in the data (e.g., 2.27% for Yoplait Original) reflects the restriction of indivisibility, not the lack of preference. The importance of demand indivisibility is also highlighted by the counterfactual study where the removal of the smallest package size (i.e., 4 oz) mainly results in nonpurchase in the yogurt category instead of switching to larger package sizes.

Détermination des stocks de sécurité dans une chaîne logistique-amont dédiée à une production de masse de produits très diversifiés

In an upstream supply chain dedicated to the mass production of customized products, many sources of production instability can be identified: the level and structure of the production of the final assembly line, the variability of lead times, the quality issues, packaging and loading constraints in transport, the anticipation of the demand, the synchronization of the flows of the components sent, received and produced. In the case of periodic replenishment policies, two different safety stocks are needed for every plant of the supply chain, which prevent from these various sources of fluctuations: a safety stock of produced components to face up to the demand of its downstream links and a safety stock of supplied components to face up to its production. The mobilized procedures must take into account the organizational framework of the exchanges of information and products. The relevance of the supply and production rules is based on the relevance of structural information broadcast along the supply chain.

Maternal effects on offspring size and packaging constraints in the whelk

Life-history theory predicts an optimal offspring size, irrespective of reproductive effort; however, in some species offspring size correlates positively with maternal size. We examine hypotheses for why this latter situation should occur in the whelk Buccinum undatum. The trade-offs between aspects of reproduction in whelks are complicated due to the provision of protective egg capsules. Many eggs are placed within each capsule but c. 99% of these eggs are consumed by the remaining developing young. Large maternal size results in more eggs, larger eggs, more eggs consumed per hatchling, more capsules, larger capsules, more eggs per capsule, a larger number of hatchlings per capsule and larger hatchlings. Increased intra-capsule and post-hatch sibling competition may decrease the marginal value for additional young and select for larger young, however, our data do not support this explanation. Instead, packaging constraints within each capsule limit the size of hatchlings but this constraint is relaxed for medium to large females because they produce large capsules. Small females appear to produce young below optimum size because of the space constraint thus explaining the correlation between maternal size and offspring size.

Ferro-Electrically Enhanced Proximity Communication.

Capacitively-coupled communication between chips, commonly known as PxC, represents a new class of I-O signaling that offers substantially improved off-chip bandwidth density. However, this form of communication presents a challenge from a packaging perspective, since tight chip alignment tolerances are required to maintain high signal fidelity and avoid cross coupling between neighboring channels. To mitigate the packaging constraints, capacitive coupling between the communication pads can be enhanced with materials that have high dielectric coefficients. Here, ferroelectrics hold promise over contemporary low- and high-k dielectrics, however their processing conditions need to be better understood and the compatibility with CMOS circuitry has to be established during integration with a back end of the line process module. In this paper we present experimental results on microfabrication modules for various families of ferroelectrics when monolithically deposited on Silicon. Additionally, we report their associated dielectric properties as extracted by measured capacitance enhancements in our fabricated devices. In this work Strontium Titanate and Barium Strontium Titanate films are sputter deposited on platinum atop Silicon. Capacitive measurements were accomplished by microfabricating electrodes atop these structures in geometries that are size and shape dependant. Dielectric coefficients as high as 400 times that of air are measured.

Cloning human herpes virus 6A genome into bacterial artificial chromosomes and study of DNA replication intermediates

Cloning of large viral genomes into bacterial artificial chromosomes (BACs) facilitates analyses of viral functions and molecular mutagenesis. Previous derivations of viral BACs involved laborious recombinations within infected cells. We describe a single-step production of viral BACs by direct cloning of unit length genomes, derived from circular or head-to-tail concatemeric DNA replication intermediates. The BAC cloning is independent of intracellular recombinations and DNA packaging constraints. We introduced the 160-kb human herpes virus 6A (HHV-6A) genome into BACs by digesting the viral DNA replicative intermediates with the Sfil enzyme that cleaves the viral genome in a single site. The recombinant BACs contained also the puromycin selection gene, GFP, and LoxP sites flanking the BAC sequences. The HHV-6A-BAC vectors were retained stably in puromycin selected 293T cells. In the presence of irradiated helper virus, supplying most likely proteins enhancing gene expression they expressed early and late genes in SupT1 T cells. The method is especially attractive for viruses that replicate inefficiently and for viruses propagated in suspension cells. We have used the fact that the BAC cloning "freezes" the viral DNA replication intermediates to analyze their structure. The results revealed that HHV-6A-BACs contained a single direct repeat (DR) rather than a DR-DR sequence, predicted to arise by circularization of parental genomes with a DR at each terminus. HHV-6A DNA molecules prepared from the infected cells also contained DNA molecules with a single DR. Such forms were not previously described for HHV-6 DNA.

The Design of a Milner CVT using Simulation Based Design of Experiments

The Milner continuously variable transmission (MCVT) is a traction drive transmission based on rolling contacts analogous to those found in angular contact roller bearings. The MCVT is applicable to very high power density applications or those with demanding packaging constraints, due primarily to the existence of multiple traction contacts on each of the rolling elements. The transmission has been modeled analytically and then Design of Experiments (DoE) techniques have been applied to create response surface model sets describing performance criteria over a wide range of design input factors. The response surface models have then been interrogated to find optimal solutions. The results show that it is possible to create a transmission with a significantly higher ratio range (10:1), compared with 5:1 that is typical for existing designs. The results also indicated that the traction patch spin factor could also be reduced over the existing designs and it is hypothesized that this should lead to an increase in efficiency. Finally, research into the stresses set up by the rolling contact indicated that stress is highest at the greatest reductions in ratio and that maximum stress appears to be proportional to the ratio range of the transmission. Hence a design optimization tool has been developed allowing engineers to rapidly optimize geometries of the MCVT to achieve desired trade-offs between ratio range, ratio position, transmission life/durability and transmission efficiency.

The 30th anniversary of quasispecies

The meeting on ‘Quasispecies: past, present and future’ took place between 17 and 18 November 2008, in Barcelona, Spain, and was organized by J. Gomez, C. Lopez‐Galindez, M.A. Martinez & A. Mas. ![][1] A meeting was held in Barcelona, Spain, in November 2008 to celebrate the 30th anniversary of the publication of the article that described the extensive genetic heterogeneity of bacteriophage Qβ (Domingo et al , 1978), which is considered to mark the beginning of experimental studies on viral quasispecies. This meeting was held at the impressive fifteenth century building of the ancient Hospital de la Santa Creu in the old town of Barcelona, which is now the headquarters of the Institut d'Estudis Catalans, and was attended by C. Weissmann (Jupiter, FL, USA), M. Billeter (Zurich, Switzerland) and E. Domingo (Madrid, Spain), who were three early protagonists of the phage Qβ work at the University of Zurich in the 1970s. Several speakers presented their results on the theoretical aspects of the population dynamics of cells and viruses, the clinical implications of quasispecies, and extensions of the quasispecies concept to cellular genes and prions. The meeting was introduced by A. Mas (Albacete, Spain), who reflected on the increasing impact that quasispecies have had in the scientific literature over the past three decades, and quoted some of the key references on viral quasispecies (Martell et al , 1992; Meyerhans et al , 1989; Najera et al , 1995; Vignuzzi et al , 2006; for a historical review of the impact of quasispecies in virology, see Holland, 2006). The scientific presentations were opened by Weissmann and Domingo, who were the last and first authors of the 1978 paper, respectively. Their talks conveyed the scientific atmosphere of the 1970s—when molecular biology was carried out with few recombinant‐DNA techniques—to a young audience. Nucleic‐acid sequencing was in … [1]: /embed/graphic-1.gif

Engine mount optimisation for vibration isolation in motorcycles

This paper presents a comprehensive model to capture the in-plane dynamics of a motorcycle system to evaluate the quality of its vibration isolation, and the design of an engine mount system. The model consists of two main structural components, the frame and the swing-arm, as well as the power-train assembly, engine mounts connecting the power-train to the frame, and the front-end assembly. The model accounts for frame and swing-arm flexibility using reduced order finite-element models. The power-train assembly is modelled as a rigid body connected to the frame through the engine mounts and to the swing-arm through a shaft assembly. The engine mounts are modelled as tri-axial spring-damper systems, and the front-end assembly is modelled as a lumped mass. The complete vehicle model is used to solve the engine mount optimisation problem, so as to minimise the total force transmitted to the frame while meeting packaging and other constraints. The mount system parameters – stiffness, position and orientation vectors – are used as design variables for the optimisation problem. The imposed loads include forces and moments due to engine imbalance as well as loads transmitted due to high amplitude, low frequency bump loads, through the tyre patch. Since packaging constraints play a significant role in a motorcycle layout, it is, therefore, important to determine the displacement envelope of the power-train under extreme loading conditions to ensure clearance with other components around the power-train. A motorcycle mount system should ideally be able to isolate the frame under steady-state loading conditions and at the same time limit the maximum excursion of the power-train under transient loading conditions.

Functional cystic fibrosis transmembrane conductance regulator expression in cystic fibrosis airway epithelial cells by AAV6.2-mediated segmental trans-splicing.

Cystic fibrosis is characterized by deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR), a Cl(-) transporter. The packaging constraints of adeno-associated viral (AAV) vectors preclude delivery of both an active promoter and CFTR cDNA to target cells. We hypothesized that segmental trans-splicing, in which two AAV vectors deliver the 5' and 3' halves of the CFTR cDNA, could mediate splicing of two pre-mRNAs into a full-length, functional CFTR mRNA. Using a segmental trans-splicing 5' donor-3' acceptor pair that split the CFTR cDNA between exons 14a and 14b, cotransfection of donor and acceptor plasmids into CFTR(-) cells resulted in full-length CFTR message and protein. Microinjection of plasmids into CFTR(-) cells produced cAMP-activated Cl(-) conductance. Vectors created with an engineered human serotype, AAV6.2, were used to deliver CFTR donor and acceptor constructs, resulting in full-length CFTR mRNA and protein as well as cAMP-activated Cl(-) conductance in CFTR(-) cells, including human CF airway epithelial IB3-1 cells. Thus, segmental trans-splicing can be used with AAV vectors to mediate expression of CFTR, a strategy potentially applicable to individuals with CF.