UWB for multi-gigabit/s communications beyond 60 GHz

The recently allocated 71–76 GHz and 81–86 GHz bands provide an opportunity for realizing Line Of Sight (LOS) links for directional point-to-point “last mile” applications. An efficient use of this spectrum may allow wireless to finally “catch up” with wires, leading to systems such as “multi-Gigabit wireless Ethernet,” and “wireless fiber.” However, the transmission at such a frequency range is characterized by several additional challenges compared to lower frequency bands, from both technological and propagation point of view, which makes difficult to use them efficiently. In this scenario, IR (Impulse Radio) UWB (Ultra Wide Band) technology might offer some more degrees of freedom for the design of a highly integrated and low cost transceiver. This work has at its core the design and BER (Bit Error Rate) performance evaluation of an IR-UWB architecture based on an 85 GHz up-conversion stage of train of Gaussian pulses having duration lower than 1 ns. Finally, we compare performance of this architecture with the ones of a more traditional continuous wave communications system with FSK (Frequency Shift Keying) modulation. Simulation results show that BER performance, in presence of RF non-linearities, for an IR-UWB transceiver architecture operating at 85 GHz (with same data rate and bandwidth) are better than a coherent BFSK scheme working in a similar scenario. Finally, some conclusions are reported, pointing out the UWB antenna design and the future works related to the modeling of the channel at frequencies beyond 60 GHz and the implementation of the test bed.     

A dependency annotation scheme for Bangla treebank

Dependency grammar is considered appropriate for many Indian languages. In this paper, we present a study of the dependency relations in Bangla language. We have categorized these relations in three different levels, namely intrachunk relations, interchunk relations and interclause relations. Each of these levels is further categorized and an annotation scheme has been developed. Both syntactic and semantic features have been taken into consideration for describing the relations. In our scheme, there are 63 such syntactico–semantic relations. We have verified the scheme by tagging a corpus of 4167 Bangla sentences to create a treebank (KGPBenTreebank).     

Multiscale Modeling of the Effect of Micro-alloying Mn and Sb on the Viscoplastic Response of SAC105 Solder

This study investigates the time-dependent viscoplastic response of two relatively new SAC105-X solders—SAC105-05Mn (Sn_1.0Ag_0.5Cu (SAC105) doped with 0.05 wt.% Mn), and SAC105-55Sb (SAC105 doped with 0.55 wt.% Sb). The results showed that the addition of Mn or Sb increases the creep resistance of SAC105 solder by one to two orders of magnitude at the tested stress levels of 2–20 MPa. The addition of Mn as a fourth alloying element promotes homogeneous distribution of micron-scale Cu₆Sn₅ intermetallic compounds (IMCs), thereby reducing their interparticle spacing as compared to that of SAC105. On the other hand, addition of Sb does not change the spacing of the Cu₆Sn₅ particle, but promotes the formation of uniformly sized Sn dendritic lobes, homogeneously distributed in the whole solder joint. Moreover, Sb also forms a solid solution with Sn and strengthens the Sn matrix in SAC105-55Sb itself. The effects of these microstructural changes (obtained using image processing) on the secondary creep constitutive response of SAC105 solder interconnects were then modeled using a mechanistic multiscale creep model. The mechanistic model was able to accurately capture the trends in the secondary creep constitutive response of the alloys and to explain the improvement in creep resistance of SAC105 due to the addition of Mn and Sb.     

Mobile touch screen device use and associations with musculoskeletal symptoms and visual health in a nationally representative sample of Singaporean adolescents

This study aimed to describe contemporary technology use, especially smartphones and tablets (mobile touch screen devices), and examine associations with musculoskeletal symptoms and visual health among adolescents in Singapore. A representative sample of 1884 adolescents (50.4% girls) from grades primary 5 to post-secondary (10–18?years old), recruited from 13 schools, completed an online questionnaire in class. Total technology use was high, with smartphone duration being highest (mean?=?264 [SD?=?243] min/day). Patterns of use, including multitasking and bout length, were influenced by gender, school level, type of device and activities. Musculoskeletal discomfort and visual symptoms were commonly reported. After adjusting for potential confounders, more hours/day of smartphone use was associated with increased risk of neck/shoulders, upper back, arms and wrist/hand discomfort (OR?=?1.04[95%CI?=?1.01–1.07] to 1.07[1.03–1.10]) and visual symptoms (OR?=?1.05[1.02–1.08]), but was associated with decreased odds of myopia (OR?=?0.97[0.94–0.99]). No significant associations were found for tablet use.

Practitioner Summary: 1884 adolescents in Singapore completed an in-depth questionnaire regarding their use of technology. The smartphone was the device with the highest usage, and greater smartphone use was associated with increased odds of musculoskeletal and visual symptoms. High use of smartphones has physical health implications for adolescents.