bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Modeling and Analysis of Lead-Free Solder Extrusion for the Design of Reliability
Authors: Lee Youngtak , Link Doug
Published: November 2016

Due to rapid growth of the microelectronics industry, packaged devices with small form factors, low costs, high power performance, and increased efficiency have become of high demand in the market. To realize the current market development trend, flip chip interconnection and System-in-Package (SiP) are some of the promising packaging solutions developed. However, a surprising amount of surface mount technology (SMT) defects are associated with the use of lead-free solder paste and methods by which the paste is applied. Two such defects are solder extrusion and tombstoning. Through the use of design of experiments (DOE), lead-free solder defect causes can be better understood and subsequently reduced or eliminated. This paper will examine the failure modes of solder extrusion and tombstoning that occurred when two different types of lead-free solders, Sn-Ag-Cu (SAC) and BiAgX were used within a SiP for attachment of surface mount devices (SMD) chip components. The systematic investigation will include the comprehensive failure analysis of the SMD components and compare the modeling and analysis of the two different solder types utilizing the design of experiments methods.
Reliability Analysis of Lead-Free Solder Joints with Solder Doping on Harsh Environment
Authors: Zhao Cong , Sanders Thomas , Hai Zhou , Shen Chaobo , Evans John L.
Published: November 2016

This paper investigates the effect of long term isothermal aging and thermal cycling on the reliability of lead-free solder mixes with different solder compositions, PCB surface finishes, and isothermal aging conditions. A variety of surface mount components are considered, including ball grid arrays (BGAs), quad flat no-lead packages (QFNs) and 2512 Surface Mount Resistors (SMRs). 12 lead-free solder pastes are tested; for BGA packages these are reflowed with lead-free solder spheres of SAC105, SAC305 and matched doped solder spheres (“matched” solder paste and sphere composition). Three surface finishes are tested: Organic Solderability Preservative (OSP), Immersion Silver (ImAg), and Electroless Nickel Immersion Gold (ENIG). All test components are subjected to isothermal aging at 125°C for 0 or 12 months, followed by accelerated thermal cycle testing from −40°C to 125°C. Data from the first 1500 cycles is presented here, with a focus on the effect of surface finish on package reliability. Current results demonstrate that the choice of surface finish has a strong effect on reliability. However, different solder materials appear to show different reliability trends with respect to the surface finishes, and the reliability trends of BGA and SMR packages also diverge.
How Mitigation Techniques Affect Reliability Results for BGAs
Authors: Caswell Greg , Keener (Black and Decker) Melissa
Published: November 2016

Since 2006 RoHS requirements have required lead free solders to take the place of tin-lead solders in electronics. The problem is that in some environments the lead free solders are less reliable than the older tin-lead solders. One of the ways to solve this problem is to corner stake, edge bond or underfill the components. When considering what mitigation technique and material to use, the operating conditions must be characterized. The temperature range is important when selecting a material to use since the glass transition temperature (Tg) and coefficient of thermal expansion (CTE) are important properties. If improperly chosen, the mitigation material can cause more failures than an unmitigated component.

This study focused on 208 I/O BGAs on a 4 layer FR4 board. There were three solders tested; two lead free (SAC305 and SN100C) and one leaded (SnPb). Three mitigation techniques were tested: corner staking, edge bonding, and underfilling. Each of these techniques had two mitigation materials tested. One material was reworkable and the other was not. The boards were subjected to mechanical shock testing and sinusoidal vibration testing until failure.

The results of the testing show that no one mitigation technique is best for all of the conditions tested. The same is true for the mitigation material. The best choice of mitigation technique and material is application dependent.
High Speed Serial Interfaces in 2.5D Integrated Systems
Authors: Chaudhary Muhammad Waqas , Heinig Andy
Published: November 2016

High speed communication has been a topic of great interest in the last decade due to excessively high data rates required between chips especially pushed by the measurement equipment industry to support extremely high bandwidth data sampling. Serial communication is chosen to support these data rates which are pushing further and further into higher data rate regimes. It is important to understand how the 2.5D integration of chips on the interposer can support serial communication and what the designer can do to leverage the special features of interposer channel to achieve lower power and higher speed. This paper will present the interposer complete channel full 3D Electromagnetic simulation based model extraction. It also presents the simulation of channel with real serial communication transmitter and receiver circuit models to describe the proposed interposer performance for multi Gb/s data rates. Also a comparison is shown for different settings of transmitter and receiver circuits under the interposer channel.
Process development and material characterization of Cu-Cu thermo-compression bonding (TCB) for high-conductivity electrical interconnects.
Authors: Bajwa Adeel , Marathe Niteesh , Jangam SivaChandra , Pal Saptadeep , Liu Ping-Yu , Goorsky Mark , Iyer Subramanian S.
Published: November 2016

In this work, we focus on metal-metal Thermo-Compression Bonding (TCB) for realizing assembly of dielets to a silicon interconnect fabric (IF). The popular metal choices include bare Cu, Cu plated with Au and Au. Our approach simplifies the metallurgies used in classic chip-to-package assemblies by avoiding the use of solder and the concomitant issues of intermetallic formation such as electrical resistance and brittleness. In this paper, we address TCB parameter optimization and material characteristics of these metal-metal TCB joints. The roles of two physical mechanisms on Cu-Cu interface voiding i.e. surface roughness prior to TCB, oxide presence at bonding interface are evaluated in detail.
Ultra-thin glasses for semiconductor packaging
Authors: Sprengard Ruediger , Jotz Matthias , Letz Martin , Parthier Lutz , Prince Fredrik , Woehrmann Markus , Thomas J.-U. , Toepper Michael
Published: November 2016

Glasses are homogeneous, many glasses have excellent dielectric properties at GHz frequencies and some have thermal expansions (CTE) which are close to silicon. Ultrathin glasses (UTG) with thicknesses of 25 μm to 200 μm (0.001 to 0.0079 inch) offer numerous options for packaging, integration and co-processing in semiconductor manufacturing processes. We introduce SCHOTT UTG including paths to further improve their mechanical stability and strength. We use laser ablation in 50μm thick glass and show via fabrication with a potential of mass manufacturing with via diameters of 30μm, 38μm pitch and a position accuracy of +/− 1μm. The structures are metallized using sputtering and electroplating which leads to hermetic, tight conducting through glass-vias (TGV).
High Thermal Conductive Die Attach Paste Using Polymer and Micron Size Silver for Power Semiconductor Package
Authors: Jin Howard (Hwail) , Xu Kewei , Naungayan Loreto , Quinones Jose
Published: November 2016

Power semiconductor package manufactures and electronic device suppliers have been looking for Pb-free alternative to traditional high Pb solder die attach adhesives. Lead solders have high thermal conductivity, 30–50W/mK, and known process with some difficulties in high volume mass production such as void, bond line control, and requiring reducing atmosphere such as forming gas. Lead is now categorized as hazardous substance to human body and environment and its products are scheduled to be banned within a few years. Standard silver epoxy pastes and Electrically Conductive Adhesives (ECSs) are other forms of die attach adhesives but the thermal conductivity is not adequate for Power devices. Eutectic gold-tin solder (80Au20Sn) has 57W/mK but it is high cost material. Currently Silver sintering material has become popular for electronic device because it has high thermal conductivity (150~250W/mK) by using nano silver sintering. But it requires high bonding temperature and pressure. It makes brittle bonding structure and has limitation in die size due to high stress.

New silver sintering material in this paper is composed of micron size silver and organic polymer. This technology overcomes all the limitations of conventional silver epoxy, eutectic gold thin solder and silver sintering product by using the unique design of polymer composition. This new silver sintering technology using polymer and micron size silver is a cost effective solution to replace Pb solder for power device and the thermal performance is almost same as nano silver sintering products. The application process is the same as standard silver epoxy and does not require new equipment. It is a cost effective drop in solution.
Hormone receptor expression in human fascial tissue
Authors: Fede C. , Albertin G. , Petrelli L. , Sfriso M.M. , Biz C. , De Caro R. , Stecco C.
Published: November 2016

Many epidemiologic, clinical, and experimental findings point to sex differences in myofascial pain in view of the fact that adult women tend to have more myofascial problems with respect to men. It is possible that one of the stimuli to sensitization of fascial nociceptors could come from hormonal factors such as estrogen and relaxin, that are involved in extracellular matrix and collagen remodeling and thus contribute to functions of myofascial tissue. Immunohistochemical and molecular investigations (real-time PCR analysis) of relaxin receptor 1 (RXFP1) and estrogen receptor-alpha (ERÎ±) localization were carried out on sample of human fascia collected from 8 volunteers patients during orthopedic surgery (all females, between 42 and 70 yrs, divided into pre- and post-menopausal groups), and in fibroblasts isolated from deep fascia, to examine both protein and RNA expression levels. We can assume that the two sex hormone receptors analyzed are expressed in all the human fascial districts examined and in fascial fibroblasts culture cells, to a lesser degree in the post-menopausal with respect to the pre-menopausal women. Hormone receptor expression was concentrated in the fibroblasts, and RXFP1 was also evident in blood vessels and nerves. Our results are the first demonstrating that the fibroblasts located within different districts of the muscular fasciae express sex hormone receptors and can help to explain the link between hormonal factors and myofascial pain. It is known, in fact, that estrogen and relaxin play a key role in extracellular matrix remodeling by inhibiting fibrosis and inflammatory activities, both important factors affecting fascial stiffness and sensitization of fascial nociceptors.
Near vision correction and work productivity among textile workers
Authors: Naidoo Kovin S. , Jaggernath Jyoti , Chinanayi Farai S. , Chan Ving F.
Published: November 2016

Purpose: Uncorrected presbyopia (near vision impairment) is prevalent in approximately 517 million people worldwide; this prevalence ranges from 30% to 80% in Africa. Good near vision is needed for a range of tasks; therefore, uncorrected presbyopia can negatively affect the quality of life of individuals, impact families and society, and potentially have negative implications on employment and labour work productivity. This study aimed to determine the impact of near vision correction on the work productivity of clothing factory workers.Methods: We conducted a cross-sectional study and sampled all workers who were aged 40 years and older and who performed near vision tasks (e.g. machinist, cutter, zip sewer, clothing pressers and quality controllers) in seven clothing factories. We included workers who were employed for at least 3 months and whose uncorrected near visual acuity could be improved and corrected to better than 6/9 with spectacle correction. Workers were provided with near vision spectacles, and changes in their work productivity were evaluated after 6 months, using the factories’ output records as an indicator for measurement.Results: The final sample comprised 268 individuals, with 56% of African origin (n = 151) and 49% (n = 115) Indian origin. There were mainly females (94%) in the sample, and the average age was 48 years (± 5.5 years, range 40–62 years). The overall post-correction mean production score (70.5 [SD ± 19.9]) was significantly higher than the overall pre-correction mean production score (67.0 [SD ±20.3]) (p < 0.001). The average change in production score was 3.5 (95% confidence interval [CI] 2.7–4.3), and the percent difference was 6.4% (95% CI 5.2–7.7). The increase in work productivity was significant for individuals of African (p < 0.001) and Indian origins (p < 0.001) but not for those of mixed race (p = 0.364; n = 2). Post-correction, the production scores of women increased significantly by 6.6% (95% CI 5.3–7.9) (p < 0.001). Significant increases in production scores were recorded for machinists, clothing pressers and quality controllers.Conclusion: Significant changes in work productivity among the workers with presbyopic correction were recorded. The clothing industry served as a favourable setting to examine changes in work productivity, obtaining reliable scores of output. This study was used as an exploratory investigation, and the results will be used to inform a randomised-controlled study that will provide stronger validation for the hypothesis that near vision correction impacts work productivity
Women in mining still exploited and sexually harassed
Authors: Botha Doret
Published: November 2016

Orientation: Globally, women have become an essential part of the mining workforce. Among other jobs, they fulfil management positions, operate heavy machinery and are involved in artisanal mining processes. In South Africa, new mining legislation not only prohibits the exclusion of women but requires from companies to actively change the demographic profile of their workforce. Mining companies are obliged to also employ women in core mining activities. Although well intended, women appointed in core positions work side by side with men, often in isolation, and are frequently at risk of sexual abuse and/or harassment.Research purpose: This research determined perceptions regarding the occurrence of sexual harassment among women working in core mining positions.Motivation for the study: Currently, there is a paucity of published data on the occurrence of sexual harassment in the mining industry.Method: A mixed-method research design was used including quantitative and qualitative research paradigms. Quantitative data were collected by means of a structured questionnaire. Qualitative data were collected by means of individual and group interviews.Main findings: From the literature review and the empirical findings, it is evident that women are still exploited and sexually harassed in the mining industry. Incidents taking place on a daily basis vary from whistling; name calling; use of vulgar or derogatory language; display of body parts; physical contact, ranging from touching to sexual assault and rape; to the exchange of sexual favours for promotion.Practical/managerial implications: It is evident from the research that a holistic approach is required to effectively eradicate sexual harassment in the mining industry, involving the commitment of relevant state departments, human resource managers and labour experts.Contribution: Practical recommendations are made to effectively address sexual harassment in the mining industry.
Patellofemoral Joint Arthroplasty: Our Experience in Isolated Patellofemoral and Bicompartmental Arthritic Knees
Authors: Sabatini L. , Schirò M. , Atzori F. , Ferrero G. , Massè A.
Published: November 2016

Introduction

Isolated patellofemoral (PF) arthritis is rare, and there is no complete agreement about the best surgical treatment. The operative treatments are total knee arthroplasty and patellofemoral replacement (PFR). The incidence of many early complications of PF arthroplasty has decreased with the introduction of newer designs. Nowadays, the main cause of revision surgery is the progression of tibiofemoral osteoarthritis. In the past, PF arthroplasty was contraindicated in patients with evidence of osteoarthritis or pain in medial or lateral tibiofemoral compartments. The improvement in implant designs and surgical techniques has allowed the addition of a monocompartmental arthroplasty for the medial or lateral tibiofemoral compartment. In this work, we evaluate our first experience with PF arthroplasty and its combination with unicompartmental knee arthroplasty.

Materials and Methods

From May 2014 to March 2016, we treated 14 patients. An isolated PF arthroplasty was performed in six knees (five patients), and a combined PF and unicompartmental knee arthroplasty was performed in nine cases. We observed a significant improvement in the clinical and functional Knee Society Scores (KSSs) after surgery in our patients.

Results

We obtained good results in our cases both for clinical and functional KSSs. Patellar clunk was recorded in one case.

Discussion and Conclusion

We are going toward a new attitude in which partial osteoarthritic changes could be treated with partial resurfacing prosthetic solutions such as unicompartmental, bi–unicompartmental or PFR alone, or unicompartmental combined, which respects the cruciates and achieves maximal bone preservation, which is vital, particularly, for young patients.
Technical study of Germolles’ wall paintings: the inputof imaging technique
Authors: Degrigny Christian , Piqué Francesca , Papiashvili Nutsa , Guery Julien , Mansouri Alamin , Le Goïc Gaëtan , Detalle Vincent , Martos-Levif Dominique , Mounier Aurélie , Wefers Stefanie , Tedeschi Cristina , Cucchi Marco , Vallet Jean-Marc , Pamart Anthony , Pinette Matthieu
Published: November 2016

The Château de Germolles is one of the rare palace in France dating from the 14th century. The noble floor is decorated with wall paintings that are a unique example of courtly love spirit that infused the princely courts of the time. After being concealed sometime in the 19th century, the paintings were rediscovered and uncovered in the middle of the 20th century and partly restored at the end of the 1990s. No scientific documentation accompanied these interventions and important questions, such as the level of authenticity of the mural decorations and the original painting technique(s) used in the medieval times remained unanswered. The combined scientific and financial supports of COSCH Cost Action and DRAC-Burgundy enabled to study Germolles’ wall paintings using some of the most innovative imaging and analytical techniques and to address some of the questions raised. The study provided significant information on the material used in the medieval times and on the conservation condition of the paintings. The data collected is vast and varied and exposed the owners of the property to the challenges of data management.
Exploración de las posibilidades de la librería Three-js en proyectos de difusión del patrimonio cultural
Authors: Palomar-Vazquez Jesús , Viñals-Blasco María José
Published: November 2016

For whatever project related with the study and conservation of cultural heritage, the dissemination stage of tree-dimensional (3D) information must be a key part of the whole process. Most of the existing web-based platforms are using WebGL technology to disseminate 3D content through Web navigators, despite they are normally generic, with a low level of viewers ‘customization. Alternatively, users can make use of several libraries, most of them open source, which allow a complete adaptation to the specific project features, even though enough level of programming skills are necessary to use them. In the present paper we will describe the minimum requirements that any cultural heritage dissemination project should contain and its implementation using Three-js, one of the most versatile open source libraries for 3D visualization. In addition, we will show several examples of Three-js integration with other libraries that take advantage from HTML5 (HyperText Markup Language, version 5) to enhance the user's experience on a Web platform.
Reconstrucción virtual 3D del coro del Convento de Santa Clara de Toro (Zamora): la recuperación de un ámbito medieval de devoción femenina mediante el registro fotogramétrico y técnicas de renderización
Authors: Gutiérrez Baños Fernando , Morillo Rodríguez Francisco M. , San José Alonso Jesús I. , Fernández Martín Juan José
Published: November 2016

The Convent of Santa Clara in Toro (Zamora) was founded in the mid-13th century. After destruction during the Castilian civil struggles of the last years of this century, its fabric was rebuilt and it was inhabited again by the Clarissan nuns, who still occupy it.  Its architecture corresponds for the most part to its early-14th century rebuilding, even though it is concealed by works carried out from the 16th to the 18th centuries, so that it is apparently a Baroque complex.  In the 1950s, in the choir of this Medieval hidden structure, a set of wall paintings of the mid-14thcentury was brought to light (one of the most important set of wall paintings of the early Gothic period ever found in Castile), but they were immediately detached from the walls and sold. It was only after a combination of circumstances that they came back to Toro to be installed in another building, the church of San Sebastián de los Caballeros, transformed into a museum. As a consequence of all these operations, the arrangement and sense of these wall paintings was lost. The virtual three-dimensional (3D) reconstruction, based on a deep analysis and criticism of historical sources and on a close inspection and photogrammetric recording of the original room once occupied by the wall paintings, enables us to place them back in their original context through the use of rendering techniques, so recovering one of the most exciting spaces of female devotion of the Castilian 14thcentury.
Evaluation of the effectiveness of HDR tone-mapping operators for photogrammetric applications
Authors: Suma Rossella , Stavropoulou Georgia , Stathopoulou Elisavet K. , Van Gool Luc , Georgopoulos Andreas , Chalmers Alan
Published: November 2016

The ability of High Dynamic Range (HDR) imaging to capture the full range of lighting in a scene has meant that it is being increasingly used for Cultural Heritage (CH) applications. Photogrammetric techniques allow the semi-automatic production of 3D models from a sequence of images. Current photogrammetric methods are not always effective in reconstructing images under harsh lighting conditions, as significant geometric details may not have been captured accurately within under- and over-exposed regions of the image. HDR imaging offers the possibility to overcome this limitation, however the HDR images need to be tone mapped before they can be used within existing photogrammetric algorithms. In this paper we evaluate four different HDR tone-mapping operators (TMOs) that have been used to convert raw HDR images into a format suitable for state-of-the-art algorithms, and in particular keypoint detection techniques. The evaluation criteria used are the number of keypoints, the number of valid matches achieved and the repeatability rate. The comparison considers two local and two global TMOs. HDR data from four CH sites were used: Kaisariani Monastery (Greece), Asinou Church (Cyprus), Château des Baux (France) and Buonconsiglio Castle (Italy).
Particulate matter (PM) episodes at a suburban site in Hong Kong: evolution of PM characteristics and role of photochemistry in secondary aerosol formation
Authors: Qin Yi Ming , Li Yong Jie , Wang Hao , Lee Berto Paul Yok Long , Huang Dan Dan , Chan Chak Keung
Published: November 2016

Abstract. Episodes with high concentrations of particulate matter (PM) across the seasons were investigated during four 1-month campaigns at a suburban site in Hong Kong. High-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) measurements revealed that both regional transport and secondary formation contributed to high PM levels during the episodes at this site. Based on distinct meteorological conditions, episodes were categorized into three types: liquid water content (LWC), solar irradiance (IR), and long-range transport (LRT). Despite the difference in meteorological conditions, all episodes were characterized by a high fraction of sulfate (45–56 %) and organics (23–34 %). However, aerosols in LWC episodes were less aged, consisting of the lowest fraction of secondary organic aerosol (SOA) and the highest fraction of small particles. Large particles mixed internally while freshly formed small particles mixed externally in LWC episodes. Aerosols in LRT episodes, by contrast, were the most aged and consisted of the highest proportion of low-volatility oxygenated organic aerosol (LVOOA) and the lowest proportion of small particles. Both small and large particles mixed externally in LRT episodes. The highest proportion of semi-volatile oxygenated organic aerosol (SVOOA) and a medium proportion of small particles were observed in IR episodes. Both small and large particles were likely externally mixed during IR episodes. Furthermore, aerosols experienced the most dramatic size increase and diurnal variation, with a time lag between SVOOA and LVOOA and a gradual increase in carbon oxidation state (OSc ≈ 2 × O : C − H : C). Five out of 10 episodes were of the IR type, further reflecting the importance of this type of episode. The evolution of aerosol components in one particular episode of the IR type, which exhibited a clear land–sea breeze pattern, was examined in detail. Sulfate and SOA due to photochemical aging were very efficiently produced during the course of 6 h. The “less-oxidized” SOA (SVOOA) was initially formed at a higher rate than the “more-oxidized” SOA (LVOOA). The SVOOA transformed to LVOOA at the later stage of photochemical aging. This transformation was further supported by mass spectral analysis, which showed an increase in the most oxidized ion (CO2+) and decreases in moderately oxidized ones (C2H3O+, C3H3O+ and C3H5O+). By measuring the physical and chemical properties of PM in a highly time-resolved manner, the current study was able to demonstrate the dynamic and complex nature of PM transformation during high-PM episodes.
North African dust transport toward the western Mediterranean basin: atmospheric controls on dust source activation and transport pathways during June–July 2013
Authors: Schepanski Kerstin , Mallet Marc , Heinold Bernd , Ulrich Max
Published: November 2016

Abstract. Dust transported from north African source region toward the Mediterranean basin and Europe is a ubiquitous phenomenon in the Mediterranean region. Winds formed by large-scale pressure gradients foster dust entrainment into the atmosphere over north African dust source regions and advection of dust downwind. The constellation of centers of high and low pressure determines wind speed and direction, and thus the chance for dust emission over northern Africa and transport toward the Mediterranean. We present characteristics of the atmospheric dust life cycle determining dust transport toward the Mediterranean basin with focus on the ChArMEx (Chemistry-Aerosol Mediterranean Experiment) special observation period in June and July 2013 using the atmosphere–dust model COSMO-MUSCAT (COSMO: COnsortium for Small-scale MOdeling; MUSCAT: MUltiScale Chemistry Aerosol Transport Model). Modes of atmospheric circulation are identified from empirical orthogonal function (EOF) analysis of the geopotential height at 850 hPa and compared to EOFs calculated from 1979–2015 ERA-Interim reanalysis. Two different phases are identified from the first EOF, which in total explain 45 % of the variance. They are characterized by the propagation of the subtropical ridge into the Mediterranean basin, the position of the Saharan heat low and the predominant Iberian heat low, and discussed illustrating a dipole pattern for enhanced (reduced) dust emission fluxes, stronger (weaker) meridional dust transport, and consequent increased (decreased) atmospheric dust concentrations and deposition fluxes. In the event of a predominant high-pressure zone over the western and central Mediterranean (positive phase), a hot spot in dust emission flux is evident over the Grand Erg Occidental, and a reduced level of atmospheric dust loading occurs over the western Mediterranean basin. The meridional transport in northward direction is reduced due to prevailing northerly winds. In case of a predominant heat low trough linking the Iberian and the Saharan heat low (negative phase), meridional dust transport toward the western Mediterranean is increased due to prevailing southerly winds resulting in an enhanced atmospheric dust loading over the western Mediterranean. Altogether, results from this study illustrate the relevance of knowing dust source location and characteristics in concert with atmospheric circulation. The study elaborates on the question of the variability of summertime dust transport toward the Mediterranean and Europe with regard to atmospheric circulation conditions controlling dust emission and transport routes of Saharan dust, exemplarily for the 2-month period of June–July 2013. Ultimately, outcomes from this study contribute to the understanding of the variance in dust transport into a populated region.
Wintertime enhancements of sea salt aerosol in polar regions
consistent with a sea-ice source from blowing snow
Authors: Huang Jiayue , Jaeglé Lyatt
Published: November 2016

Abstract. Sea salt aerosols (SSA) are generated via air bubbles bursting at the ocean surface, as well as by wind mobilization of saline snow and frost flowers over sea-ice covered areas. The relative magnitude of these sources remains poorly constrained over polar regions, affecting our ability to predict their impact on halogen chemistry, cloud formation and climate. We implement a blowing snow and a frost flower emission scheme in the GEOS-Chem global chemical transport model, which we validate against multi-year (2001–2008) in situ observations of SSA mass concentrations at three sites in the Arctic, two sites in coastal Antarctica, as well as during a cruise in the Arctic (ICEALOT, 2008). A simulation including only open ocean emissions underestimates SSA mass concentrations by factors of 2–10 during winter-spring for all ground-based and ship-based observations. When blowing snow emissions are added, the model is able to reproduce observed wintertime SSA concentrations, with the model bias decreasing from a range of −80 % to −34 % for the open ocean simulation to −2 % to +9 % for the simulation with blowing snow emissions. We find that the frost flower parameterization cannot fully explain the high wintertime concentrations and displays a seasonal cycle decreasing too rapidly in early spring. Furthermore, the high day-to-day variability of observed SSA is better reproduced by the blowing snow parameterization. Over the Arctic (Antarctic), we calculate that submicron SSA emissions from blowing snow account for 1.0 (2.5) Tg yr−1, while frost flower emissions lead to 0.25 (0.14) Tg yr−1 compared to 0.78 (1.0) Tg yr−1 from the open ocean. Blowing snow emissions are largest in regions where persistent strong winds occur over sea ice (East of Greenland, over the central Arctic, Beaufort Sea, as well as the Ross and Weddell Seas). In contrast, frost flower emissions are largest where cold air temperatures, open leads and mild winds are co-located (over the Canadian Arctic Archipelago, coastal regions of Siberia, and off the Ross and Ronne ice shelves). Overall, in situ observations of mass concentrations of SSA suggest that blowing snow is likely to be the dominant SSA source during winter, with frost flowers playing a much smaller role.
Sulfate geoengineering: a review of the factors controlling the
needed injection of sulfur dioxide
Authors: Visioni Daniele , Pitari Giovanni , Aquila Valentina
Published: November 2016

Abstract. Sulfate geoengineering has been proposed as an affordable and climate-effective means for temporarily offset the warming produced by the increase of well mixed greenhouse gases (WMGHG). This climate engineering technique has been planned for a timeframe of a few decades needed to implement global inter-governmental measures needed to achieve stabilization of the atmospheric content of WMGHGs (CO2 in particular). The direct radiative effects of sulfur injection in the tropical lower stratosphere can be summarized as increasing shortwave scattering with consequent tropospheric cooling and increasing long- wave absorption with stratospheric warming. Indirect radiative effects are related to induced changes in the ozone distribution, stratospheric water vapor abundance, formation and size of upper tropospheric cirrus ice particles and lifetime of longlived species, namely CH4 in connection with OH changes through several photochemical mechanisms. A direct comparison of the net effects of WMGHG increase with direct and indirect effects of sulfate geoengineering may help fine-tune the best amount of sulfate to be injected in an eventual realization of the experiment. However, we need to take into account large uncertainties in the estimate of some of these aerosol effects, such as cirrus ice particle size modifications.
On the efficiency of the hybrid and the exact second-order sampling formulations of the EnKF: a reality-inspired 3-D test case for estimating biodegradation rates of chlorinated hydrocarbons at the port of Rotterdam
Authors: Gharamti Mohamad E. , Valstar Johan , Janssen Gijs , Marsman Annemieke , Hoteit Ibrahim
Published: November 2016

Abstract. This study considers the assimilation problem of subsurface contaminants at the port of Rotterdam in the Netherlands. It involves the estimation of solute concentrations and biodegradation rates of four different chlorinated solvents. We focus on assessing the efficiency of an adaptive hybrid ensemble Kalman filter and optimal interpolation (EnKF-OI) and the exact second-order sampling formulation (EnKFESOS) for mitigating the undersampling of the estimation and observation errors covariances, respectively. A multi-dimensional and multi-species reactive transport model is coupled to simulate the migration of contaminants within a Pleistocene aquifer layer located around 25 m below mean sea level. The biodegradation chain of chlorinated hydrocarbons starting from tetrachloroethene and ending with vinyl chloride is modeled under anaerobic environmental conditions for 5 decades. Yearly pseudo-concentration data are used to condition the forecast concentration and degradation rates in the presence of model and observational errors. Assimilation results demonstrate the robustness of the hybrid EnKF-OI, for accurately calibrating the uncertain biodegradation rates. When implemented serially, the adaptive hybrid EnKF-OI scheme efficiently adjusts the weights of the involved covariances for each individual measurement. The EnKFESOS is shown to maintain the parameter ensemble spread much better leading to more robust estimates of the states and parameters. On average, a well tuned hybrid EnKF-OI and the EnKFESOS respectively suggest around 48 and 21 % improved concentration estimates, as well as around 70 and 23 % improved anaerobic degradation rates, over the standard EnKF. Incorporating large uncertainties in the flow model degrades the accuracy of the estimates of all schemes. Given that the performance of the hybrid EnKF-OI depends on the quality of the background statistics, satisfactory results were obtained only when the uncertainty imposed on the background information is relatively moderate.
Evaluating performance of simplified physically based models for shallow landslide susceptibility
Authors: Formetta Giuseppe , Capparelli Giovanna , Versace Pasquale
Published: November 2016

Abstract. Rainfall-induced shallow landslides can lead to loss of life and significant damage to private and public properties, transportation systems, etc. Predicting locations that might be susceptible to shallow landslides is a complex task and involves many disciplines: hydrology, geotechnical science, geology, hydrogeology, geomorphology, and statistics. Two main approaches are commonly used: statistical or physically based models. Reliable model applications involve automatic parameter calibration, objective quantification of the quality of susceptibility maps, and model sensitivity analyses. This paper presents a methodology to systemically and objectively calibrate, verify, and compare different models and model performance indicators in order to identify and select the models whose behavior is the most reliable for particular case studies.The procedure was implemented in a package of models for landslide susceptibility analysis and integrated in the NewAge-JGrass hydrological model. The package includes three simplified physically based models for landslide susceptibility analysis (M1, M2, and M3) and a component for model verification. It computes eight goodness-of-fit indices by comparing pixel-by-pixel model results and measurement data. The integration of the package in NewAge-JGrass uses other components, such as geographic information system tools, to manage input–output processes, and automatic calibration algorithms to estimate model parameters. The system was applied for a case study in Calabria (Italy) along the Salerno–Reggio Calabria highway, between Cosenza and Altilia. The area is extensively subject to rainfall-induced shallow landslides mainly because of its complex geology and climatology. The analysis was carried out considering all the combinations of the eight optimized indices and the three models. Parameter calibration, verification, and model performance assessment were performed by a comparison with a detailed landslide inventory map for the area. The results showed that the index distance to perfect classification in the receiver operating characteristic plane (D2PC) coupled with the model M3 is the best modeling solution for our test case.
The physics behind Van der Burgh's empirical equation, providing a new predictive equation for salinity intrusion in estuaries
Authors: Zhang Zhilin , Savenije Hubert H. G.
Published: November 2016

Abstract. The practical value of the surprisingly simple Van der Burgh's equation to predict saline water intrusion in alluvial estuaries is well documented, but the physical foundation of the equation is still weak. In this paper we provide a connection between the empirical equation and the theoretical literature, leading to a theoretical range for the Van der Burgh's coefficient of 1/2
Revisiting Tropical Instability Wave Variability in the Atlantic Ocean using SODA reanalysis
Authors: Takanaca de Decco Hatsue , Rebelo Torres Junior Audalio , Ponzi Pezzi Luciano , Landau Luiz
Published: November 2016

Abstract. The spatial and temporal variability of energy exchange in Tropical Instability Waves (TIWs) in the Atlantic Ocean were investigated. A spectral analysis was used to filter the 5-day mean results from Simple Ocean Data Assimilation reanalysis spanning from 1958 to 2008. TIWs were filtered over periods of 15 to 60 days and between wavelengths of 4 and 20 longitude degrees. The main approach of this study was the use of bidirectionally filtered TIW time series as the perturbation fields, and the difference in these time series from the SODA total results was considered to be the basic state for energetics analysis. The main result was that the annual cycle (period of ~ 360 days) was the main source of variability of the waves, and the semi-annual cycle (period of ~ 180 days) was a secondary variation, which indicated that TIWs occurred throughout the year but with intensity that varies seasonally. Barotropic instability acts as the mechanism that feeds and extracts energy to/from TIWs as alternate zonal bands at equatorial Atlantic. Baroclinic instability is the main mechanism that extracts energy from TIWs to the equatorial circulation north of Equator. All TIW patterns of variability were observed at west of ~ 10º W. The present study reveals new evidences regarding TIW variability and suggests that future investigations should include a detailed description of TIW dynamics as part of Atlantic Ocean equatorial circulation
Using Landsat Thematic Mapper (TM) sensor to detect change in land surface temperature in relation to land use change in Yazd, Iran
Authors: Zareie Sajad , Khosravi Hassan , Nasiri Abouzar , Dastorani Mostafa
Published: November 2016

Abstract. Land surface temperature (LST) is one of the key parameters in the physics of land surface processes from local to global scales, and it is one of the indicators of environmental quality. Evaluation of the surface temperature distribution and its relation to existing land use types are very important to the investigation of the urban microclimate. In arid and semi-arid regions, understanding the role of land use changes in the formation of urban heat islands is necessary for urban planning to control or reduce surface temperature. The internal factors and environmental conditions of Yazd city have important roles in the formation of special thermal conditions in Iran. In this paper, we used the temperature–emissivity separation (TES) algorithm for LST retrieving from the TIRS (Thermal Infrared Sensor) data of the Landsat Thematic Mapper (TM). The root mean square error (RMSE) and coefficient of determination (R2) were used for validation of retrieved LST values. The RMSE of 0.9 and 0.87 °C and R2 of 0.98 and 0.99 were obtained for the 1998 and 2009 images, respectively. Land use types for the city of Yazd were identified and relationships between land use types, land surface temperature and normalized difference vegetation index (NDVI) were analyzed. The Kappa coefficient and overall accuracy were calculated for accuracy assessment of land use classification. The Kappa coefficient values are 0.96 and 0.95 and the overall accuracy values are 0.97 and 0.95 for the 1998 and 2009 classified images, respectively. The results showed an increase of 1.45 °C in the average surface temperature. The results of this study showed that optical and thermal remote sensing methodologies can be used to research urban environmental parameters. Finally, it was found that special thermal conditions in Yazd were formed by land use changes. Increasing the area of asphalt roads, residential, commercial and industrial land use types and decreasing the area of the parks, green spaces and fallow lands in Yazd caused a rise in surface temperature during the 11-year period.
Presence of rapidly degrading permafrost plateaus in south-central Alaska
Authors: Jones Benjamin M. , Baughman Carson A. , Romanovsky Vladimir E. , Parsekian Andrew D. , Babcock Esther L. , Stephani Eva , Jones Miriam C. , Grosse Guido , Berg Edward E.
Published: November 2016

Abstract. Permafrost presence is determined by a complex interaction of climatic, topographic, and ecological conditions operating over long time scales. In particular, vegetation and organic layer characteristics may act to protect permafrost in regions with a mean annual air temperature (MAAT) above 0 °C. In this study, we document the presence of residual permafrost plateaus in the western Kenai Peninsula lowlands of south-central Alaska, a region with a MAAT of 1.5 ± 1 °C (1981–2010). Continuous ground temperature measurements between 16 September 2012 and 15 September 2015, using calibrated thermistor strings, documented the presence of warm permafrost (−0.04 to −0.08 °C). Field measurements (probing) on several plateau features during the fall of 2015 showed that the depth to the permafrost table averaged 1.48 m but at some locations was as shallow as 0.53 m. Late winter surveys (augering, coring, and GPR) in 2016 showed that the average seasonally frozen ground thickness was 0.45 m, overlying a talik above the permafrost table. Measured permafrost thickness ranged from 0.33 to  >  6.90 m. Manual interpretation of historic aerial photography acquired in 1950 indicates that residual permafrost plateaus covered 920 ha as mapped across portions of four wetland complexes encompassing 4810 ha. However, between 1950 and ca. 2010, permafrost plateau extent decreased by 60.0 %, with lateral feature degradation accounting for 85.0 % of the reduction in area. Permafrost loss on the Kenai Peninsula is likely associated with a warming climate, wildfires that remove the protective forest and organic layer cover, groundwater flow at depth, and lateral heat transfer from wetland surface waters in the summer. Better understanding the resilience and vulnerability of ecosystem-protected permafrost is critical for mapping and predicting future permafrost extent and degradation across all permafrost regions that are currently warming. Further work should focus on reconstructing permafrost history in south-central Alaska as well as additional contemporary observations of these ecosystem-protected permafrost sites south of the regions with relatively stable permafrost.
Tensiones mundiales, multipolaridad relativa y bloques de poder en una nueva fase de la crisis del orden mundial
Authors: Merino Gabriel Esteban
Published: November 2016

Nos encontramos ante una nueva fase la crisis del orden mundial, cuya característica principal es el enfrentamiento político directo y en territorios principales entre los bloques de poder centrales del “norte global” y los bloques de poder emergentes, profundizando la situación de multipolaridad relativa. Esta nueva situación, que podemos ubicar a partir del estallido del conflicto en Ucrania, es presentada resumidamente en este trabajo a partir de los siguientes puntos: 1) el planteamiento del problema (qué está en juego en Ucrania) en relación a la crisis del orden  mundial; 2) el eje estratégico Moscú-Beijing, los BRICS y el enfrentamiento con “Occidente”; 3) “Occidente” y sus posiciones: las diferencias estratégicas en Estados Unidos y las contradicciones con el núcleo euro (Alemania-Francia); 4) el impacto y los desafíos sobre América Latina como bloque de poder emergente.
A preeminência na América do Sul como fundamento da política externa brasileira entre 1945 e 1964.
Authors: Saboya André Nassim de
Published: November 2016

A política externa brasileira entre o fim do Estado Novo e o Golpe de 1964 é caracterizada, em grande medida, pelo desenvolvimentismo e a busca pela industrialização do país. Analistas desse processo geralmente focam-se no aspecto econômico e nos interesses das elites civis, enquanto a busca por poder e preeminência é pouco ressaltada. Desse modo, um dos principais objetivos dos Estados na arena internacional é ignorado. O desenvolvimento econômico e industrial não deve ser considerado um fim em si mesmo, visto que o progresso material serve a determinado objetivo, que, para o Estado, é o aumento do poder. Esse artigo busca retomar a geopolítica como um dos fundamentos para a política externa e para o desenvolvimento brasileiros no século XX, levando-se em conta a teoria pioneira de Mario Travassos, voltada para a preeminência na América do Sul, e a história da política externa brasileira ao longo da República Nova (1945-1964).