Packaging Technology for Dielectric-Coating-Less Heavy Ion Radiation Testing of High-Voltage (HV) Electronic Parts

Testing high voltage (HV) electronic parts (greater than 300 V) for sudden event effects (SEE) caused by cosmic rays in the space environment, consisting of energetic heavy-ions, and neutron radiation in the upper atmosphere is a crucial step towards using these parts in spacecraft and aircraft. Due to the nature of cosmic radiation and neutrons, electronic parts are tested for SEE without any packaging and/or shielding over the top of the device. In the case of commercial HV parts, the top of the packaging is etched off and then a thin dielectric coating is placed over the part in order to avoid electrical arcing between the device surface and wire bonds and other components. Even though the effects of the thin dielectric layer on SEE testing can be accounted for, the dielectric layer significantly hinders post testing failure analysis. Replicating the test capability of state-of-the-art packaging while eliminating the need for post radiation test processing of the die surface (that obscures failure analysis) is the goal. To that end, a new packaging concept for HV parts has been developed that requires no dielectric coating over the part. Testing of prototype packages used with Schottky diodes (rated at 1200V) has shown no electrical arcing during testing and leakage currents during reverse bias testing are within the manufactures specifications

Causal shadow and non-local modular flow: from degeneracy to perturbative genesis by correlation

Causal shadows are bulk space-time regions between the entanglement wedges and the causal wedges, their existence encodes deep aspects of the entanglement wedge reconstruction in the context of subregion duality in AdS/CFT. In this paper, we study the perturbation theory of the causal shadows and their relation to the properties of the associated modular flows. We first revisit the cases of degenerate causal shadows based on known examples, and discuss the origin for their degeneracy via the local nature of the modular flow. We then focus on the perturbative case in which the CFT subregion consists of two spheres separated by a large distance $L\gg R_{1,2}$. The RT surfaces still agree with the causal horizons, giving a degenerate causal shadow classically. We compute the corrections to the quantum extremal surfaces (Q.E.S) from the bulk mutual information, which then give rise to a non-degenerate causal shadow at order $G_N$. We end by discussing the causal shadow perturbation theory more generally, in particular we explore the possibility of extracting the positivity conditions characterizing perturbative causal shadows in the boundary CFTs.Comment: 42 page

In-line measuring of dissolved carbon dioxide

Tässä työssä tutkittiin liuenneen hiilidioksidin pitoisuuden in-line-määrittämismenetelmää prosessiteollisuuden tarpeisiin. Menetelmässä mitattava neste erotetaan membraanilla kuivasta mittatilasta, josta pitoisuus määritellään huoneilman hiilidioksidipitoisuuden määrittämiseen tarkoitetulla analysaattorilla. Tutkimus tehtiin K-Patents Oy:n tiloissa Vantaalla työtä varten suunnitellulla mittausastialla. Tutkimukseen valittiin ei-huokoisia polymeerimembraaneja, jotka olivat taustatutkimuksen perusteella parhaiten soveltuvat kyseiseen sovellukseen. Membraanien suorituskykyä ja mekaanista kestävyyttä tutkittiin liuottamalla puhdasta hiilidioksidia deionisoituun veteen eri lämpötiloissa ja paineissa. Mittaukset suoritettiin jaksoittain siten, että mittaustila puhdistettiin ensin puhtaalla ilmalla, jonka jälkeen hiilidioksidin annettiin virrata mittaustilaan ja sen hiilidioksidipitoisuuden kasvua seurattiin. Menetelmään liittyvää laskentaa varten luotiin membraanien hiilidioksidin läpäisyn malli, jonka tarkoitus on kuvata mitattavan nesteen hiilidioksidipitoisuuden ja mittaustilan pitoisuuden kasvunopeuden yhteyttä. Laboratoriokokeiden tulosten perusteella määritettiin vakiot, joilla pitoisuus saadaan laskettua kokeissa käytetyillä membraaneilla. Mittatiedot kerättiin K-Patents Oy:n kehittämällä sulautetulla tiedonkeruuelektroniikalla, joka oli yhteydessä tietokoneeseen, johon tiedot tallennettiin ja jolla niiden analysointi suoritettiin. Tässä työssä kehitetyllä menetelmällä saatiin määritettyä nesteen hiilidioksidipitoisuus membraanin erottamasta mittaustilasta kohtuullisella tarkkuudella, joskin parannettavaa on erityisesti membraanin suorituskyvyssä korkeissa paineissa. Menetelmään perustuvan in-line-prosessimittalaitteen kehittäminen on mahdollista tutkimalla uusia membraanivaihtoehtoja, kehittämällä laitteen mekaanisia ominaisuuksia, ja selvittämällä mallin lämpötilariippuvuudet.A method for in-line measuring of dissolved carbon dioxide for process industries was developed in this thesis. In the method a semipermeable membrane is used to separate process liquid from a dry measure chamber, where the measuring is done using a room air carbon dioxide probe. The research was done in K-Patents Oy's laboratory in Vantaa, Finland using the test vessel designed for this work. Non-porous polymer membranes were selected as the most suitable for this application based on literature research. Their performance and mechanical durability was studied by dissolving carbon dioxide gas into deionized water in different temperatures and pressures. The measurements were done in periods that can be divided into two stages: first the measurement chamber was purged with dry air and then the changes in concentration of the carbon dioxide was measured and analyzed. A model for the carbon dioxide permeation was created for calculating the carbon dioxide concentration indirectly. The model connects the concentration in the measured liquid and the concentration changes in the measure chamber. Data from the sensors was collected by using electronics designed by K-Patents and they were connected to a computer where the actual analyzing was done. The analyzed experiment results were used to define constants in the permeation model. The method created in this thesis was proven to work but it is noted that its accuracy needs improvements. Especially membranes' performance in high pressures must be improved. However, the method is promising and an in-line process sensor implementing this carbon dioxide measurement method is possible to develop by exploring better membrane materials, improving sensor's mechanical properties and defining the model's temperature dependencies

To Answer or Not to Answer? Improving Machine Reading Comprehension Model with Span-based Contrastive Learning

Machine Reading Comprehension with Unanswerable Questions is a difficult NLP task, challenged by the questions which can not be answered from passages. It is observed that subtle literal changes often make an answerable question unanswerable, however, most MRC models fail to recognize such changes. To address this problem, in this paper, we propose a span-based method of Contrastive Learning (spanCL) which explicitly contrast answerable questions with their answerable and unanswerable counterparts at the answer span level. With spanCL, MRC models are forced to perceive crucial semantic changes from slight literal differences. Experiments on SQuAD 2.0 dataset show that spanCL can improve baselines significantly, yielding 0.86-2.14 absolute EM improvements. Additional experiments also show that spanCL is an effective way to utilize generated questions

Vitexin alleviates neuropathic pain in a mouse chronic constriction injury model by inactivation of NF-κB

Purpose: To investigate the therapeutic effect of vitexin on neuropathic pain (NP) in a mouse model of chronic constriction injury (CCI).Methods: The CCI model was established by four chronic ligatures in the sciatic nerve. Vitexin was intraperitoneally administered (10 mg/kg, once daily) for 21 days. Mechanical withdrawal threshold (MWT) and paw withdrawal latency (PWL) were determined before and after the establishment of CCI model. The spinal cords were collected to measure mRNA levels by reverse-transcriptase polymerase chain reaction (RT-PCR) enzyme-linked immunosorbent assay (ELISA). Western blot was used to examine protein expression levels.Results: Vitexin reversed the CCI-induced reduction in MWT and PWL values, indicating that it lowered mechanical hypersensitivity response and hyperalgesia caused thermal stimulation (p < 0.05). The elevated levels of IL-6, IL-1β, and TNFα observed in CCI-treated mice were also inhibited by vitexin, suggesting that it suppressed pro-inflammatory cytokines. Moreover, vitexin attenuated CCI-induced activation of NF-κB signaling in CCI-treated mice (p < 0.05).Conclusion: Vitexin alleviates NP by inhibiting pro-inflammatory cytokines and NF-κB signaling in CCItreated mice. Thus, it is a potential target for NP treatment. Keywords: Vitexin, Neuropathic pain, Chronic constriction injury, Mechanical hypersensitivity, Hyperalgesia, NF-κ

Response of the metastable pitting corrosion of laser powder bed fusion produced Ti–6Al–4v to H+ concentration changes

There is limited research on metastable pitting corrosion in an acidic environment, and acid is a major challenge for material corrosion. Therefore, this work investigated the metastable pitting corrosion of laser powder bed fusion (LPBF)-produced Ti–6Al–4V, in Hank’s solution, at different pH values (pH = 3, 5, and 7). This work investigated the effect of acid on the characteristics of passive films, as well as the change in metastable pitting behavior. Based on the results of electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS), the passive film will be inhibited and dissolved under the influence of H+. The higher the concentration of H+, the thinner the passive film. Potentiodynamic polarization tests reveal that LPBFed Ti–6Al–4V in Hank’s solution, at pH 3, has more obvious metastable pitting corrosion. This is because the higher the H+ concentration, the more Cl- is adsorbed on the surface of the passive film, which is prone to generate soluble chlorides by competitive adsorption with oxygen atoms and thus develop into metastable pitting corrosion

Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires

NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19′ martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19′ martensitic transformation, and (V) plastic deformation of the specimen