An on-engine method for dynamic characterisation of NOx concentration sensors

An on-engine method for dynamic characterisation of automotive NOx concentration sensors is presented. Steps in start of injection on a diesel engine are employed to achieve step-like NOx concentration variations on exhaust flow. On the basis of the sensor response, delay and dynamic response can be easily identified; the paper shows a simple least squares procedure although other models and identification techniques could be used. Application data is presented for three NOx sensors: a research-grade chemiluminescence exhaust gas analyser, and two different commercial ZrO2-based sensors. © 2010 Elsevier Inc.The authors thanks R. Lujan and G. Couture for their valuable contribution in the experimental part of the present work. This work has been partially supported by Ministerio de Ciencia y Tecnologia through Project PLANUCO No. TRA2006-15620-C02-02.Galindo, J.; Serrano Cruz, JR.; Guardiola, C.; Blanco-Rodriguez, D.; Cuadrado, I. (2011). An on-engine method for dynamic characterisation of NOx concentration sensors. Experimental Thermal and Fluid Science. 35(3):470-476. https://doi.org/10.1016/j.expthermflusci.2010.11.010S47047635

Family firm internationalization: Past research and an agenda for the future

Although the study of family firm internationalization has generated considerable scholarly attention, existing research has offered varied and at times incompatible findings on how family ownership and management shape internationalization. To improve our understanding of family firm internationalization, we systematically review 220 conceptual and empirical studies published over the past three decades, structuring our comprehensive overview of this field according to seven core international business (IB) themes. We assess the literature and propose directions for future research by developing an integrative framework of family firm internationalization that links IB theory with conceptual perspectives used in the reviewed body of work. We propose a research agenda that advocates a cross-disciplinary, multi-theoretic, and cross-level approach to studying family firm internationalization. We conclude that family firm internationalization research has the potential to contribute valuable insights to IB scholarship by increasing attention to conceptual and methodological issues, including micro-level affective motivations, background social institutions, temporal perspectives, and multi-level analyses

Characterization of the pressure losses in a common rail diesel injector

A methodology to characterise the pressure losses in quasi-steady conditions (i.e. at full needle lift) of common rail diesel injectors was developed. The aim was to quantify the error when experimental results of nozzle internal flow are compared with CFD results, where pressure losses are usually neglected. The proposed methodology is based mainly on experimental tests that are complemented with some approximate calculations, based on the physics of the phenomenon, to take into account the effect of the needle deformation. The results obtained in the work lead to two important conclusions: on the one hand, that it is dangerous to extrapolate results relative to the injection (internal flow, spray atomization, spray penetration˙ ..) and combustion processes from low permeability nozzles (e.g. single-hole nozzles) to high permeability nozzles (e.g. multi-hole nozzles), and, on the other hand, that the comparison of these results between experiments and CFD simulations should be carried out carefully, because the pressure losses in the injector can be high under certain conditions. Finally, people working on the study of the injection and/or combustion processes, through experiments or simulations, will find here some interesting information to better know the actual injection pressure to be used in their analysis and/or simulations.The PhD studies of Oscar A. de la Garza were funded by the FPU program of the Ministerio de Educacion of Spain (grant no. AP2008-01913).López, JJ.; Salvador Rubio, FJ.; De La Garza De Leon, O.; Arregle, JJP. (2012). Characterization of the pressure losses in a common rail diesel injector. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 226(12):1697-1706. https://doi.org/10.1177/0954407012447020S169717062261

Clinical Characteristics and Outcomes of Patients With Cutibacterium acnes Endocarditis

Importance: It is suggested that patients with Cutibacterium acnes endocarditis often present without fever or abnormal inflammatory markers. However, no study has yet confirmed this statement. Objective: To assess the clinical characteristics and outcomes of patients with C acnes endocarditis. Design, Setting, and Participants: A case series of 105 patients presenting to 7 hospitals in the Netherlands and France (4 university hospitals and 3 teaching hospitals) with definite endocarditis according to the modified Duke criteria between January 1, 2010, and December 31, 2020, was performed. Clinical characteristics and outcomes were retrieved from medical records. Cases were identified by blood or valve and prosthesis cultures positive for C acnes, retrieved from the medical microbiology databases. Infected pacemaker or internal cardioverter defibrillator lead cases were excluded. Statistical analysis was performed in November 2022. Main Outcomes and Measures: Main outcomes included symptoms at presentation, presence of prosthetic valve endocarditis, laboratory test results at presentation, time to positive results of blood cultures, 30-day and 1-year mortality rates, type of treatment (conservative or surgical), and endocarditis relapse rates. Results: A total of 105 patients (mean [SD] age, 61.1 [13.9] years; 96 men [91.4%]; 93 patients [88.6%] with prosthetic valve endocarditis) were identified and included. Seventy patients (66.7%) did not experience fever prior to hospital admission, nor was it present at hospitalization. The median C-reactive protein level was 3.6 mg/dL (IQR, 1.2-7.5 mg/dL), and the median leukocyte count was 10.0 × 103/µL (IQR, 8.2-12.2 × 103/µL). The median time to positive blood culture results was 7 days (IQR, 6-9 days). Surgery or reoperation was indicated for 88 patients and performed for 80 patients. Not performing the indicated surgical procedure was associated with high mortality rates. Seventeen patients were treated conservatively, in accordance with the European Society of Cardiology guideline; these patients showed relatively high rates of endocarditis recurrence (5 of 17 [29.4%]). Conclusions and Relevance: This case series suggests that C acnes endocarditis was seen predominantly among male patients with prosthetic heart valves. Diagnosing C acnes endocarditis is difficult due to its atypical presentation, with frequent absence of fever and inflammatory markers. The prolonged time to positivity of blood culture results further delays the diagnostic process. Not performing a surgical procedure when indicated seems to be associated with higher mortality rates. For prosthetic valve endocarditis with small vegetations, there should be a low threshold for surgery because this group seems prone to endocarditis recurrence.</p

Semiempirical in-cylinder pressure based model for NOx prediction oriented to control applications

This work describes the development of a fast NO X predictive model oriented to engine control in diesel engines. The in-cylinder pressure is the only instantaneous input signal required, along with several mean variables that are available in the ECU during normal engine operation. The proposed model is based on the instantaneous evolution of the heat release rate and the adiabatic flame temperature (both obtained among other parameters from the in-cylinder pressure evolution). Corrections for considering the NO X reduction due to the re-burning mechanism are also included. Finally, the model is used for providing a model-based correction of tabulated values for the NO X emission at the reference conditions. The model exhibits a good behaviour when varying exhaust gas recirculation rate, boost pressure and intake temperature, while changes in the engine speed and injection settings are considered in the tabulated values. Concerning the calculation time, the model is optimised by proposing simplified sub-models to calculate the heat release and the adiabatic flame temperature. The final result is suitable for real time applications since it takes less than a cycle to complete the NO X prediction.Guardiola García, C.; López Sánchez, JJ.; Martín Díaz, J.; García Sarmiento, D. (2011). Semiempirical in-cylinder pressure based model for NOx prediction oriented to control applications. Applied Thermal Engineering. 31(16):3275-3286. doi:10.1016/j.applthermaleng.2011.05.048S32753286311

Family involvement and firms’ establishment mode choice in foreign markets

Extant literature on foreign entry increasingly recognizes firms’ heterogeneity as a potential reason for inconsistency in results on the establishment mode choice, i.e. whether and under which conditions firms should choose to enter a new country through a greenfield investment or an acquisition. Our study contributes to this debate by identifying family ownership and family involvement in management as potential powerful sources of such heterogeneity. Integrating international business studies with both corporate finance literature on family firms and recent contributions from the Socio Emotional Wealth perspective on family ownership, we claim that, due to greater risk aversion and lower access to information, the family involvement either in the firm ownership and management leads to a higher propensity towards greenfield initiatives (vs. acquisitions). However, we also find that such a propensity decreases with international experience especially in family-owned firms given the greater ability of professionalized management to overcome family-related concerns on making acquisitions. Our analysis on 1,045 foreign initiatives undertaken by 311 Italian family and non-family firms between 2003 and 2013 confirms our expectations – indicating family ownership as a significant driver of international business choices

Explaining the effect of rapid internationalization on horizontal foreign divestment in the retail sector. An extended penrosean perspective

Building on and extending Penrosean logic we argue that rapid international expansion by firms might lead to a breach of Penrosean constraints on efficient expansion and to subsequent divestment of international operations to bring firm scope back into Penrosean constraints. We further predict that intra-regional concentration and international experience moderate the above effect because they influence firms ability to avoid a breach of Penrosean constraints and/or weaken the consequences of such a breach. Using data on the international expansion and divestment of large retail MNEs over the period 2003-2012 we find empirical support for the proposed extended Penrose effect in explaining international divestment as well as for the moderating effects of intra-regional concentration and international experience. Our study contributes to the development of Penrosean logic and to our understanding of the factors that drive firms to divest overseas operations